US20130291569A1

US20130291569A1 - Air conditioning system performance monitor

Info

Publication number: US20130291569A1
Application number: US13/887,247
Authority: US
Inventors: Narayanan M. Subramanian
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-05-04
Filing date: 2013-05-03
Publication date: 2013-11-07

Abstract

An air-conditioning system performance monitor measures the temperature of air on either side of the evaporator. Then a microcontroller means calculates the temperature drop in the air flowing across the evaporator. If the temperature drop is less than a predetermined threshold temperature, the microcontroller means alerts the house owner via display units, alarm, internet enabled devices and cell phones to call for service. This unit can be used on central air-conditioning systems, window air-conditioning systems and automobile air-conditioning systems.

Description

PRIORITY CLAIM

This patent application claims priority from provisional U.S. patent application entitled “Air conditioning system performance monitor” having application No. 61/642,513 filed on May 4, 2012, the contents of which are incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to monitoring the performance of air-conditioning and refrigeration systems and alerting home owners or building management to call for service when system performance deteriorates.

BACKGROUND OF INVENTION

Air-conditioning systems work well when the refrigerant in the system is at the designed pressure, the air filter in the air-conditioning system is not dirty and the blower motor is operating at the designed speed. Most often, the performance of the air-conditioning system deteriorates when the refrigerant pressure is lower than designed value or when the air filter is dirty. If the air-conditioning system is run for an extended period of time with improper refrigerant pressure, dirty air filter or low blower motor speed, the air-conditioning system will consume more energy but will not cool the living space sufficiently. The compressor will run hot and it will ruin the compressor. To avoid these costly problems, it is recommended to check the air-conditioning system once a year for optimal performance. Instead of annual check-up, if the performance of the air-conditioning system can be monitored continuously, then it is possible to detect any anomaly immediately and take corrective action. This will prevent the compressor from getting ruined, save energy and save money. This invention sets out to do this in a cost effective way.

SUMMARY OF INVENTION

The primary objective of the present invention is to monitor the performance of air-conditioning systems continuously and alert the home owner when the performance deteriorates. Here home owner is used to mean both home owners in case of individual homes, drivers in case of automobiles and trucks and service personnel in case of apartment complexes, office buildings, industrial installations etc.
Another objective of the present invention is to make it easy for anyone to attach this invention to an existing air-conditioning system, whether it is at home, office or in the automobile.
A third objective is to make this invention cost effective for the consumers to buy and use.
The foregoing objectives are attained by having a programmable microcontroller monitor air temperature in the air-conditioning system for proper range and alert when the temperature difference falls outside normal temperature range.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the concept, upon which this disclosure is based, may readily be utilized as a basis for designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an evaluator means that measures air temperature, evaluates performance of the air-conditioning system and communicates performance status to a notifier means.

FIG. 2 is a block diagram of said notifier means that communicates with one or more evaluator means of FIG. 1 and with other electronic communicating devices it is configured to communicate with such as cellular phones and internet enabled devices to disseminate the performance information to the home owner.

FIG. 3 is a flowchart of the decision process used by a first embodiment of said evaluator means to determine if the air-conditioning system is operating within its design parameters and to communicate with said notifier means about the status of the air-conditioning system.

FIG. 4 is a flowchart of the decision process used by the first embodiment of said notifier means to determine when to alert the home owner to call for service. The alert may be local using alarm means and display means or through other electronic communication devices that are configured to communicate with said notifier means such as cell phones and internet enabled devices.

FIG. 5 is a block diagram of evaluator means of the second embodiment for automobile air-conditioning systems.

FIG. 6 is a flowchart of the decision process used by the second embodiment of the invention to determine if the air-conditioning system in the automobile is operating within its design parameters and to communicate the status to the driver of the automobile.

In this document, air-conditioning system means air-conditioner, air-conditioning system, refrigeration system and any system where air is drawn across an evaporator.

DETAILED DESCRIPTION OF THE INVENTION

The air-conditioning system is designed such that air flows across an evaporator and gets cooled. The design value for the air temperature drop across the evaporator in an air-conditioning system performing as per design specifications will be referred to henceforth as ideal-deltaT or IDT. With current technology, the value of IDT is about 17 degrees Fahrenheit. When the refrigerant pressure is lower than the manufacturer suggested pressure, enough cooling of the evaporator does not take place and the air temperature drop across the evaporator is less than IDT. Similarly, if the air filter is dirty, or the blower motor speed is lower than designed value, enough air does not flow past the evaporator to cool sufficiently. So by knowing the temperature drop across the evaporator of an air-conditioning system, we can determine the performance of the air-conditioning system. Because of advances in the air-conditioning technology, this value of IDT can vary in future. Still this invention can be used once the proper value of IDT is used in the performance evaluation process. A cutoff value, which is a few degrees Fahrenheit lower than IDT may be allowed before the air-conditioning system is deemed to need servicing. This cutoff value in temperature difference, at which the air-conditioning system is deemed to need servicing will henceforth be referred to as threshold temperature difference or TTD.
The first embodiment of the invention consists of a plurality of detection and evaluation means, henceforth called evaluator1_cluster and a notifier means to notify the status of air-conditioning system, henceforth called notifier1. Each detection and evaluation means in said evaluator) cluster will henceforth be referred to as evaluator1. When multiple air-conditioning systems are involved as in office buildings and large homes, each air-conditioning system will have one evaluator1. Hence said evaluator1_cluster will have a plurality of evaluator1. When there is only one air-conditioning system involved, then said evaluator1_cluster will have only one evaluator1. It would be advantageous to have a single notifier1 collect the performance status from each of a plurality of evaluator1 in said evaluator1_cluster and notify the status of a plurality of air-conditioning systems in an aggregate manner. FIG. 1 is a block diagram of the electronic circuit inside said evaluator1. For central air-conditioning systems, evaluator1 is mounted on the outside surface of plenum near the evaporator of the air-conditioning system. Referring to FIG. 1, evaluator1 consists of a first electronic circuit board, 1, with a first microcontroller means 2. First microcontroller means, 2, is in electrical communication with a first display means, 7, a first transceiver means, 8 and a plurality of temperature sensor means which are divided into a plurality of inlet air temperature sensor means, 3, and a plurality of outlet air temperature sensor means, 4. First microcontroller means is also in electrical communication with a plurality of pressure sensor means, which are divided into a first pressure sensor means, 5, and a second pressure sensor means, 6. FIG. 3 shows the decision logic used by said first microcontroller means to determine the performance of the air-conditioning system.
Said plurality of inlet air temperature sensor means, 3, are placed in the air flow just before the evaporator of the air-conditioning system. Said plurality of outlet air temperature sensor means, 4, are placed in the air flow just after the evaporator. Said first pressure sensor means is placed in the airflow just before the air filter in the air-conditioning system. Said second pressure sensor means is placed in the airflow just after said air filter. Said first microcontroller means, 2, gets air temperature information from said plurality of inlet air temperature sensor means and said plurality of outlet air temperature sensor means. It calculates the average temperature drop across the evaporator. If the calculated average temperature drop across the evaporator is greater than or equal to TTD, it means the air-conditioning system is performing optimally. In this case, it checks the status of the air-conditioning system stored in its memory during one of the previous calculations. This status that is stored in memory of said first microcontroller means will henceforth be called mc1_status. If mc1_status is good, it means that the air-conditioning system status has not changed since previous calculation. So there is no need to alert the home owner. In this case it checks said first transceiver means to see if it has received a status inquiry from said notifier1. If there is an inquiry, said first microcontroller means furnishes mc1_status to said notifier1 via said first transceiver means. In either case, whether there is a status inquiry or not, said first microcontroller means waits for predetermined wait time and then repeats the process of getting temperature information from said plurality of inlet air temperature sensor means and said plurality of outlet air temperature sensor means. In FIG. 3, this is shown via 33-34-35-36-38-47-48-49-33 process loop. If there is no status inquiry from said notifier1, then step 48 is not performed.
If, at decision point 38, mc1_status is other than good, it means that the status has now changed from other than good to good. It means that the problem experienced by the air conditioning system has been corrected. In this case, said first microcontroller means updates mc1_to good. It then displays mc1_status via said first display means, 7. Said first microcontroller means then checks said first transceiver means to see if it has received a status inquiry from said notifier1. From this point on, the process is the same as for previously stated condition. In FIG. 3, this is shown via 33-34-36-38-39-46-47-48*49-33 process loop. If there is no status inquiry from said notifier1, then step 48 is not performed.
If the calculated average temperature drop across the evaporator is less than TTD, it means either the air-conditioning system is off or that it is not performing optimally. So said first microcontroller means checks to see if the calculated average temperature drop across the evaporator is nearly equal to zero. If nearly equal to zero, it means that the air-conditioning system is presently turned off. In this case, said first microcontroller means checks said first transceiver means to see if it has received a status inquiry from said notifier1. From this point on, the process is the same as for previously stated condition. In FIG. 3, this is shown via 33-34-35-36-37-47-48-49-33 process loop. If there is no status inquiry from said notifier1, then step 48 is not performed.
If the calculated average temperature drop across the evaporator is less than TTD but not nearly equal to zero, it means that the air-conditioning system is not performing optimally. In this case, said first microcontroller means checks mc1_status. If this value represents other than good, it means that the non-optimal-performance of the air-conditioning system had already been determined in one of the previous calculation cycles. In this case, said first microcontroller means checks said first transceiver means to see if it has received a status inquiry from said notifier1. From this point on, the process is the same as for previously stated conditions. In FIG. 3, this is shown via 33-34-35-36-37-47-48-49-33 process loop. If there is no status inquiry from said notifier1, then step 48 is not performed.
If, at decision point 40, said first microcontroller means finds that mc1_status is good, it means that the air-conditioning system was working well till the previous calculation cycle. In this case, said first microcontroller means obtains pressure readings from said first pressure sensor means and said second pressure sensor means. If the two pressure readings are substantially the same, it means that the air filter is not clogged. The problem could be the blower motor speed or the refrigerant pressure in the system. Then it has to be serviced by a professional. In this case said first microcontroller means updates mc1_status to indicate that a service call should be made. After updating mc1_status, said first microcontroller means displays mc1_status via said first display means, 7. Said first microcontroller means then checks said first transceiver means to see if it has received a status inquiry from said notifier1. From this point on, the process is the same as for previously stated conditions. In FIG. 3, this is shown via 33-34-35-36-37-40-41-44-46-47-48-49-33 process loop. If there is no status inquiry from said notifier1, then step 48 is not performed.
If, at decision point 42, the two pressure readings are not almost the same, it means that the air filter is clogged and so there is a significant pressure drop across the air filter. In this case said first microcontroller means updates mc1_status to indicate that the air filter should be changed. After updating mc1_status, said first microcontroller means displays mc1_status via said first display means, 7. From this point on, the process is the same as for previously stated conditions. In FIG. 3, this is shown via 33-34-35-36-37-41-42-43-46-47-48-49-33 process loop. If there is no status inquiry from said notifier1, then step 48 is not performed.
FIG. 2 is a block diagram of the electronic circuit inside said notifier1. For homes, notifier1 is normally placed near the thermostat that controls the air-conditioning system. For office buildings and industrial establishments, it can be placed where other monitoring systems are placed. Referring to FIG. 2, notifier1 consists of a second electronic circuit board, 11, with a second microcontroller means, 12. Second microcontroller means, 12, is in electrical communication with a light sensing means, 13, a second transceiver means, 14, a second display means, 15, an alarm means, 16 and a first user input means, 17. Said second transceiver means is configured to communicate seamlessly and wirelessly with said first transceiver means of said evaluator1. It is also configured to communicate seamlessly with user specified devices such as cellular phones and internet enabled devices. FIG. 4 shows the decision logic used by said second microcontroller means to notify the status of air-conditioning system to the home owner.
Referring to FIG. 2 and FIG. 4, said second microcontroller means, 12, via said second transceiver means, 14, requests performance status from each said evaluator1 in said evaluator1 cluster. After a predetermined wait time1, it checks to see if the performance status is received from said evaluator1. If the performance status is received, it resets the retry count for that evaluator1 from which the performance status was received. Then it checks the received status value against value in its memory for this evaluator1 which will henceforth be called mc2_status. If the two values are not the same, it means that the status has changed since last check. It updates mc2_status with the received value and displays this new status on said second display means. It also communicates, via said second transceiver means, updated status to user specified devices such as cellular phones and internet enabled devices that are configured to communicate with said second transceiver means. Then it checks if the new status value corresponds to good performance. If it is not, said second microcontroller means checks to see if alarm can be sounded anytime or it should be sounded only during daytime. This is because, if the air-conditioning systems monitored are in a location where they should be working 24 hours a day and there is maintenance staff working 24 hours a day, the alarm must be sounded when adverse condition is detected. If the monitored air-conditioning system is in the house, sounding an alarm can wait till day time when people would have woken up. If said second microcontroller means is configured to activate alarm only during daytime, it checks input from said light sensing means to determine if it is daytime before activating the alarm. If it is not daytime, said second microcontroller means waits till daytime to activate said alarm. Since it may take a few days to get the air-conditioning system serviced, the homeowner may acknowledge the alarm via said first user input means or any of the user specified devices such as cellular phones and internet enabled devices that are configured to communicate with said second transceiver means. While sounding the alarm, said second microcontroller means checks input from said first user input means and said second transceiver means to see if there is a response from home owner acknowledging the alarm. If an acknowledgement is received, it deactivates the alarm, sets a wait flag to indicate to itself that after a few days or weeks, if the status has not changed, it should sound the alarm again. If there are more evaluator1 in said evaluator1_cluster to be checked, said second microcontroller means selects the next evaluator1 in evaluator1_cluster to send an inquiry via said second transceiver means. This portion of the logic is shown via 63-64-65-66-72-73-74-75-76-77-81-82-84-85-86-87-88-89-69-70-64. If said second microcontroller means is configured to activate said alarm even during night time, it bypasses checking whether it is daytime or not. This portion of the logic is shown via 63-64-65-66-72-73-74-75-77-81-85-86-87-88-89-69-70-64.
If the home owner had serviced the air-conditioning system within the predetermined servicing period, the performance status of the air-conditioning system would have been updated to good and so the alarm means would not be activated by said second microcontroller means, 12. If said second microcontroller means finds that mc2_status is good at decision point 77, it resets the wait flag, and selects the next evaluator1 in evaluator1_cluster to send an inquiry via said second transceiver means. From this point on, the process is the same as for previously stated conditions. This portion of the logic is shown via 63-64-65-66-72-73-74-75-76-77-78-79-69-70-64.
If at decision point 73, said second microcontroller means finds that the received status value is the same as mc2_status, it checks if the wait flag is set. If set, it means that the air-conditioning system status is not good. If the predetermined servicing period is over, said second microcontroller means checks to see if it can activate said alarm at any time. From this point on, the processing is the same as mentioned before. This portion of the logic is shown via 63-64-65-66-72-73-79-80-81-82-83-84-86-87-88-89-69-70-64 if alarm can be activated only during daytime and via 63-64-65-66-72-73-79-80-81-85-86-87-88-89-69-70-64 if alarm can be activated at any time. If predetermined servicing period is not over, at decision point 80, said second microcontroller means skips activating alarm. This portion of the logic is shown via 63-64-65-66-72-73-79-80-69-70-64. If the wait flag is not set at decision point 79, it means that the air-conditioning system is performing well and so said second microcontroller means selects the next evaluator1 in evaluator1_cluster to send an inquiry via said second transceiver means. From this point on, the process is the same as for previously stated conditions. This portion of the logic is shown via 63-64-65-72-73-79-69-70-64.
When said second microcontroller means sends an inquiry to said evaluator1, it expects a response back from said evaluator1 within a predetermined wait time1. If a response is not received from said evaluator1 within this time period, said second microcontroller means increments said retry count for this evaluator1. If the retry count is less than a predetermined number of tries, said second microcontroller means selects the next evaluator1 in evaluator1_cluster to send an inquiry via said second transceiver means. This portion of the logic is shown via 63-64-65-66-67-68-69-70-64. If the retry count exceeds predetermined number of tries, said second microcontroller means checks mc2_status. If mc2_status is other than check evaluator1, it means that evaluator1 was responding till the last try. So said second microcontroller means updates mc2_status to “check evaluator1”. Then it displays this updated status on said second display means. From this point on, the process is the same as for previously stated condition when said second microcontroller means had to activate the alarm. This portion of the logic is shown via 63-64-65-66-67-68-90-91-75-76-77-81-82-83-84-85-86-87-89-69-70-64 or via 63-64-65-66-67-68-90-91-75-76-77-81-86-87-88-89-69-70-64. In the next iteration, at decision point 90, mc2_status will reflect that the problem with evaluator1 is a known problem. After a predetermined servicing period, an alarm will be sounded as mentioned before. This portion of the logic is shown via 63-64-65-66-67-68-90-79-80.
When said second microcontroller means tries to select the next evaluator1 in evaluator1_cluster, if it finds that said plurality of evaluator1 has been exhausted, it waits a predetermined wait time2 and then starts with the first evaluator1 in said evaluator1_cluster to send an inquiry via said second transceiver means. This portion of the logic is shown via 69-70-71-63-64. Thus the embodiment presented is able to continuously monitor the health of the air-conditioning system and alert the home owner to any problem with the air-conditioning system.
The second embodiment of the invention is for air-conditioning systems where said plurality of inlet air temperature sensor means and said plurality of outlet air temperature sensor means cannot be placed on either side of said evaporator easily. Some examples of such systems are air-conditioning systems in automobiles and window air-conditioners. Here the evaluator means, henceforth called car_evaluator1, is mounted in the vicinity of the vent through which cold air is blown. FIG. 5 shows the block diagram for said car_evaluator1 and FIG. 6 shows the decision logic used by said car_evaluator1. In FIG. 1, FIG. 3, FIG. 5 and FIG. 6, like reference numerals designate like components and decision process. Said plurality of outlet air temperature sensor means is placed inside or very close to the vent blowing cold air and in the path of cold air. Said plurality of inlet air temperature sensor means will be sampling the air temperature in the passenger area of automobiles and interior of room in window air-conditioners. and will not be in the path of cold air blowing from the vent. For proper reading, the air circulation system should be in recycle mode. In this case, the function of notifier means can also be integrated into said car_evaluator1 itself since the driver will be there when the alarm is activated.
FIG. 5 is a block diagram of the electronic circuit inside said car_evaluator1. Referring to FIG. 5, car_evaluator1 consists of a first electronic circuit board, 1, with a first microcontroller means 2. First microcontroller means, 2, is in electrical communication with a first display means, 7, an alarm means, 21, a user input means, 20 and a plurality of temperature sensor means which are divided into a plurality of inlet air temperature sensor means, 3, and a plurality of outlet air temperature sensor means, 4. FIG. 6 shows the decision logic used by said first microcontroller means to determine the performance of the air-conditioning system.
Referring to FIG. 5 and FIG. 6, said first microcontroller means, 2, gets automobile cabin temperature information from said plurality of inlet air temperature sensor means. It gets vent air temperature from said plurality of outlet air temperature sensor means. It calculates the average temperature drop between said plurality of inlet air temperature sensor means and said plurality of outlet air temperature sensor means. If the calculated average temperature drop is greater than or equal to TTD, it means the air-conditioning system is performing optimally. In this case, it checks mc1_status. If mc1_status is good, it means that the air-conditioning system status has not changed since previous calculation. So there is no need to alert the driver of the automobile. Said first microcontroller means waits for predetermined wait time and then repeats the process of getting temperature information from said plurality of inlet air temperature sensor means and said plurality of outlet air temperature sensor means. In FIG. 6, this is shown via 53-54-36-38-49-53 process loop.
If, at decision point 38, mc1_status is other than good, it means that the status has now changed from other than good to good. It means that the owner of the automobile has corrected the problem experienced by the air conditioning system. In this case, said first microcontroller means changes mc1_status to good and displays this new status via said first display means, 7. It then waits for predetermined wait time before repeating the process of getting temperature information from said plurality of inlet air temperature sensor means and said plurality of outlet air temperature sensor means. In FIG. 6, this is shown via 53-54-35-36-38-39-46-49-53 process loop.
If the calculated average temperature drop at decision point 36 is less than TTD, it means either the air-conditioning system is turned off or that it is not performing optimally. So said first microcontroller means checks to see if the calculated average temperature drop is nearly equal to zero. If nearly equal to zero, it means that the air-conditioning system is presently turned off. In this case, it waits for predetermined wait time before repeating the process. In FIG. 6, this is shown via 53-54-35-36-37-49-53 process loop.
If the calculated average temperature drop at decision point 36 is less than TTD but not nearly equal to zero, it means that the air-conditioning system is not performing optimally. In this case, said first microcontroller means checks mc1_status. If mc1_status is other than good, it means that the non-optimal-performance of the air-conditioning system had already been determined in one of the previous calculations. In this case, it waits for predetermined wait time. From this point on, the process is the same as for previously stated conditions. In FIG. 6, this is shown via 53-54-35-36-37-40-49-53 process loop.
If, at decision point 40, said first microcontroller means finds that mc1_status is good, it means that the air-conditioning system was working well till the previous calculation cycle. In this case, said first microcontroller means updates mc1_status to indicate that a service call should be made. After updating mc1_status, said first microcontroller means displays mc1_status via said first display means, 7. From this point on, the process is the same as for previously stated conditions. In FIG. 6, this is shown via 54-35-36-37-40-44-46-49-53 process loop.
In the above discussion for both embodiments disclosed, said inlet air temperature sensor means and said outlet air temperature sensor means can be thermistors, temperature sensing infrared detector means or any other sensor means that provide an electrical output proportional to the temperature read. Said first pressure sensor means and said second pressure sensor means can be any device that can provide an electrical output proportional to the pressure read such as pressure transducers. Said first display means and said second display means can be an LCD display, a set of LED lights or a single LED light blinking at different rates to represent different mc1_statuses. Said light sensing means used for sensing ambient light level can be a photo transistor, a photo diode, a light dependent resistor, a ccd camera or any device that can detect light level in the surrounding area and provide an electrical output proportional to ambient light level. Said first user input means can be a keypad, a touch screen or just a switch.
Whenever the air-conditioning system is turned on or turned off, it will take a few minutes for the system to reach stable operating condition. Hence said first microcontroller means will take multiple readings over a period of time to make sure the air-conditioning system has reached stable operating condition. Temperature and pressure readings taken after the air-conditioning system has reached this stable operating condition are used by said first microcontroller means to determine the performance of the air-conditioning system.

Claims

What is claimed is:

1. A performance monitoring system for monitoring performance of air-conditioning systems comprising a notifier means and a plurality of evaluator means in an evaluator cluster; each said evaluator means comprising:

a) a first microcontroller means;

b) a plurality of temperature sensor means in electrical communication with said first microcontroller means;

c) a plurality of pressure sensor means in electrical communication with said first microcontroller means;

d) a first display means configured to receive display data from said first microcontroller means and display received data;

e) a first transceiver means in electrical communication with said first microcontroller means to exchange a plurality of performance data between said first microcontroller means and said notifier means;

said notifier means comprising:

a) a second microcontroller means;

b) a light sensing means in electrical communication with said second microcontroller means;

c) a second transceiver means in electrical communication with said second microcontroller means;

d) an alarm means in electrical communication with said second microcontroller means;

e) a second display means configured to receive display data from said second microcontroller means and display received data;

f) a first user input means in communication with said second microcontroller means to provide user communicated information to said second microcontroller means.

2. A performance monitoring system of claim 1 wherein said plurality of temperature sensor means are thermistors.

3. A performance monitoring system of claim 1 wherein said plurality of temperature sensor means are infrared detectors.

4. A performance monitoring system of claim 1 wherein said plurality of temperature sensor means comprise a plurality of input air temperature sensor means and a plurality of output air temperature sensor means.

5. A performance monitoring system of claim 4 wherein said plurality of input air temperature sensor means measure air temperature before air passes through evaporator in said air-conditioning system.

6. A performance monitoring system of claim 4 wherein said plurality of output air temperature sensor means measure air temperature after air passes through said evaporator in said air-conditioning system.

7. A performance monitoring system of claim 1 wherein said plurality of pressure sensor means are pressure transducers.

8. A performance monitoring system of claim 1 wherein said plurality of pressure sensor means consist of a first pressure sensor means to measure air pressure immediately before air passes through an air filter in said air-conditioning system and a second pressure sensor means to measure air pressure immediately after air passes through said air filter.

9. A performance monitoring system of claim 1 wherein said first microcontroller means is configured to:

a) accept temperature readings from said plurality of input air temperature sensor means and said plurality of output air temperature sensor means after each predetermined time interval and compute average temperature difference;

b) accept pressure readings from said plurality of pressure sensor means after each predetermined time interval and compute pressure difference;

c) determine operational state of said air-conditioning system to be operating when said computed temperature difference is substantially greater than zero;

d) determine operational state of said air-conditioning system to be turned off when said computed temperature difference is substantially equal to zero;

e) update previously stored status value to good when operational state is operating and said computed temperature difference is not less than predetermined threshold temperature difference;

f) update previously stored status value to air filter change when operational state is operating and said computed temperature difference is less than predetermined threshold temperature difference and calculated pressure difference is not substantially close to zero;

g) update previously stored status value to call service when operational state is operating and said computed temperature difference is less than predetermined threshold temperature difference and calculated pressure difference is substantially close to zero;

h) communicate said updated previosly stored value to said notifier means using said first transceiver means when requested by said notifier means;

i) communicate said updated previosly stored value to said first display means.

10. A performance monitoring system of claim 1 wherein said first display means is a LCD display.

11. A performance monitoring system of claim 1 wherein said first display means is a LED display.

12. A performance monitoring system of claim 1 wherein said first transceiver means is configured to communicate wirelessly with said second transceiver means.

13. A performance monitoring system of claim 1 wherein said light sensing means communicates ambient light level information to said second microcontroller means.

14. A performance monitoring system of claim 13 wherein said light sensing means is a photo diode.

15. A performance monitoring system of claim 13 wherein said light sensing means is a charge coupled device.

16. A performance monitoring system of claim 13 wherein said light sensing means is a light dependent resistor.

17. A performance monitoring system of claim 1 wherein said alarm means produces audible sound.

18. A performance monitoring system of claim 1 wherein said second transceiver means is configured to communicate wirelessly with a plurality of said first transceiver means of said plurality of evaluator means and a plurality of user specified cellular phones and internet enabled devices.

19. A performance monitoring system of claim 1 wherein said second microcontroller means is configured to:

a) communicate with each said evaluator means in said evaluator cluster using said second transceiver means;

b) retry predetermined number of times over a predetermined time interval to communicate with each said evaluator means before alerting user of problem with said evaluator means;

c) update previously stored status value with received status value when received status value different from previously stored status value;

d) communicate said received status value to said second display means when said received value different from said previously stored status value;

e) communicate said received status value to said plurality of user specified cellular phones and internet enabled devices when said received value different from said previously stored status value;

f) activate said alarm means at any time when said received status value is other than good;

g) activate said alarm means when said light sensing means indicates daytime and said received status value other than good and said second microcontroller means configured to activate alarm means only during daytime;

h) deactivate said alarm means when so directed;

i) update previously stored status value to check said evaluator means when no response received from said evaluator means over multiple tries over multiple predetermined time intervals.

20. A performance monitoring system of claim 1 wherein said second display means is a LCD display.

21. A performance monitoring system of claim 1 wherein said first user input means is a keyboard.

22. A performance monitoring system of claim 1 wherein said first user input means is a switch.

23. A performance monitoring system of claim 1 wherein said first user input means is a touch screen.

24. A method for monitoring performance of air-conditioning systems comprising a notifier means communicating with a plurality of evaluator means in an evaluator cluster; each said evaluator means computing temperature drop across evaporator of air-conditioning system comprising the steps:

a) providing a plurality of input air temperature sensor means capable of measuring air temperature before air passes through said evaporator in said air-conditioning system;

b) providing a plurality of output air temperature sensor means capable of measuring air temperature after air passes through said evaporator in said air-conditioning system;

c) providing a first pressure sensor means capable of measuring air pressure just before air reaches air filter in said air-conditioning system;

d) providing a second pressure sensor means capable of measuring air pressure just after air passes said air filter in said air-conditioning system;

e) providing a first microcontroller means capable of determining the performance of said air-conditioning system;

f) providing a first display means capable of receiving performance status data from said first microcontroller means and displaying to users;

g) providing a first transceiver means capable of communicating a plurality of performance data between said first microcontroller means and said notifier means.

Said notifier means performing the steps of:

h) collecting a plurality of performance data from a plurality of evaluator means in said evaluator cluster;

i) notifying performance status of each air-conditioning system to user.

25. The method of claim 24 wherein in step e) the first microcontroller means determines the performance of said air-conditioning system by:

a. accepting temperature reading from said plurality of input air temperature sensor means and said plurality of output air temperature sensor means after each predetermined time interval;

b. computing average temperature difference between said plurality of input air temperature sensor means and said plurality of output air temperature sensor means;

c. accepting pressure readings from said first pressure sensor means and said second pressure sensor means after each predetermined time interval;

d. computing pressure difference between said first pressure sensor means and said second pressure sensor means

e. determining operational state of said air-conditioning system to be operating when said computed temperature difference is substantially greater than zero;

f. determining operational state of said air-conditioning system to be turned off when said computed temperature difference is substantially equal to zero;

g. updating previously stored status value to good when operational state is operating and computed temperature difference is not less than predetermined threshold temperature difference;

h. updating previously stored status value to air filter change when operational state is operating and computed temperature difference is less than predetermined threshold temperature difference and calculated pressure difference is not substantially close to zero;

i. updating previously stored status value to call service when operational state is operating and computed temperature difference is less than predetermined threshold temperature difference and calculated pressure difference is substantially close to zero;

j. communicating said updated previosly stored value to said notifier means using said first transceiver means when requested by said notifier means;

k. communicating said updated previosly stored value to said first display means.

26. The method of claim 24 wherein in step h) the notifier means collects a plurality of performance data from a plurality of evaluator means in said evaluator cluster by:

a) communicating after every predetermined time interval, with each said evaluator means in said evaluator cluster using said second transceiver means;

b) retrying predetermined number of times over a predetermined time interval to communicate with each said evaluator means before alerting user of problem with said evaluator means;

c) updating previously stored status value with received status value when received status value different from previously stored status value;

d) communicating said received status value to said second display means when said received value different from said previously stored status value;

e) communicating said received status value to plurality of user specified cellular phones and internet enabled devices;

f) activating said alarm means any time when said received status other than good;

g) activating said alarm means when said light sensing means indicates daytime and said received status other than good and said second microcontroller means configured to activate alarm means only during daytime;

h) deactivating said alarm means when so directed by user.

i) updating previously stored status value to check said evaluator means when no response received from said evaluator means over multiple tries over multiple predetermined time intervals.

27. A performance monitoring system for monitoring performance of air-conditioning systems comprising:

a) a first microcontroller means;

c) a first display means configured to receive display data from said first microcontroller means and display received data.

d) an alarm means in electrical communication with said first microcontroller means;

e) a user input means in communication with said first microcontroller means to provide user communicated information to said first microcontroller means.

28. A performance monitoring system of claim 27 wherein said plurality of temperature sensor means are thermistors.

29. A performance monitoring system of claim 27 wherein said plurality of temperature sensor means are infrared detectors.

30. A performance monitoring system of claim 27 wherein said plurality of temperature sensor means comprise a plurality of input air temperature sensor means and a plurality of output air temperature sensor means.

31. A performance monitoring system of claim 30 wherein said plurality of input air temperature sensor means measure air temperature in automobile cabin.

32. A performance monitoring system of claim 30 wherein said plurality of output air temperature sensor means measure air temperature substantially close to automobile cabin vent.

33. A performance monitoring system of claim 27 wherein said first microcontroller means is configured to:

b) determine operational state of said air-conditioning system to be operating when said computed temperature difference is substantially greater than zero;

c) determine operational state of said air-conditioning system to be turned off when said computed temperature difference is substantially equal to zero;

d) update previously stored status value to good when operational state is operating and said computed temperature difference is not less than predetermined threshold temperature difference;

e) update previously stored status value to call service when operational state is operating and said computed temperature difference is less than predetermined threshold temperature difference;

f) communicate said updated previosly stored value to said first display means;

g) activate said alarm means when said updated previously stored status value is other than good;

h) deactivate said alarm means when so directed using user input means.

34. A performance monitoring system of claim 27 wherein said first display means is a LCD display.

35. A performance monitoring system of claim 27 wherein said first display means is a LED display.

36. A performance monitoring system of claim 27 wherein said alarm means produces audible sound.

37. A performance monitoring system of claim 27 wherein said user input means is a keyboard.

38. A performance monitoring system of claim 27 wherein said first user input means is a switch.