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George H.
George H., ASE Certified Technician
Category: Chevy
Satisfied Customers: 18270
Experience:  GM Tech ASE Master Tech 15+ years
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2002 chevy cavalier: jumped..compressor..the fuses..wiring diagram

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i have a 2002 cheve cavalier the a/c wont work it has freon in it i jumped the wire that goes to the compressor and it cut on and i charged the system. the fans cut on when i hit the a/c switch in side the car the fuses are all good i jumped the low pressure switch and the a/c compressor did not cut on.. please help. is there a hidden relay somewhere under the dash inside? i need the a/c wiring diagram maybe. ive done everything i can i chanbged the relay under hood i switched it with the fuel pump relay and the car still ran so that has to be good maybe something in car. i switched the a/c switch inside car from a car that the a/c was working in. please help

Hello I will help you with your question,



You have done most of the testing but I would be looking at the ERLS fuse in the instrument panel fuse block.


This fuse supplies power to the coil side of the relay, you checked the power side by jumping across the #30 to the #87 pins of the relay socket?


Use a test light if you have one to check for power to the relay






Let me know what you find and I will work with you from there






Customer: replied 6 years ago.
i just checked the erls fuse its good i then checked the relay under hood with my test light and power was going to the relay? now what do we do. tis is really bothering me please help bra!!!!!

Do you have power to both of the relay pin cavities? There are two sides to this relay and two fuses. The ERLS fuse supplies power to the coil and the AXC fuse which supplies power to the compressor so two pins of the relay will have power with the key in the run position


Let me know



Customer: replied 6 years ago.
i only saw one pin light red and two others blue for ground and 1 did nothing theres two relays under hood that look the same the cover is missing so i dont no which is which but the one im talking about on this reply is the first relay that both look alike that you could swicth around if you wanted. so what do you think bout what i wrote

OK here is the location of the AC fuse and the AC relay


Save this picture for future refrence



Customer: replied 6 years ago.
ok im going to check one more time on the right relay hold on a sec
Ok I will be here
Customer: replied 6 years ago.
ok i just checked all 3 prongs are red there all hot

The AC switch sends the AC request to the PCM and the PCM grounds the AC relay to turn the compressor on. Put the clip lead of your test light on the positive terminal of the battery and the tip on one of the non hot terminals with the engine running, the relay out and the AC on so that the fans run. See if you have ground at one of the non hot terminals. Unplug the compressor before you start the engine.


Let me know if you have ground at one of the terminals


Is this a testlight or what kind of tester?



Customer: replied 6 years ago.
which non hot terminals do you want me to test i got lost a little on that point sorry

You said you had three hot (powered) pin cavities in the relay block?


There are four or five pins on the relay you have?


You should have two that have power with the engine running and the AC selected on. One of the others will be the compressor so if you were to use a large paperclip to jump from one of the hot terminals to the compressor terminal the compressor would run. If you look on the relay you will see #30 and #87 or #3 and #5. Connecting these two is what the relay does when you press the AC switch


The other terminals ( #85 and #86) are the power and the ground that is supplied by the PCM and this tells the relay to connect the #87 to the #30 and the compressor turns on.


I need you to find if one of the terminals is grounded with the engine running, the AC selected on and the compressor un plugged.



Customer: replied 6 years ago.
theres 4 prongs on relay but you now theres only 3 in the box that have the metal sleeve for the prongs to make contact and work. thats y i said there 3 that are red or hot the 4th one in the box didnt have anything to make contact with.. is that bad?

You are missing a contact. There have to be 4 so you will have to disassemble the box and repair the contact. It may have been pushed down into the box.



This is the removal procedure, you will have to remove all the fuses and relays to release the plastic clips on the sides of the box and seperate it. Work slowly I do not have diagrams for the disassembly of the fuseblock.


If you are unsure about this repair you may want to replace the entire fuseblock. You can find used parts in your area at


Let me know what I can do to help you with this




George H., ASE Certified Technician
Category: Chevy
Satisfied Customers: 18270
Experience: GM Tech ASE Master Tech 15+ years
George H. and 4 other Chevy Specialists are ready to help you

I cannot contact you through email. The terms of service of this site only allow communication on the question page so anytime you login to the JA site this question will be in the MY QUESTONS list and when you post to it I will be notified and I will respond as soon as I see you have made a post



Thanks for accepting my help


I am curious about what you find so please let me know once you have had time to swap the boxes or have repaired the original box


No need to reply until you know or unless you have further questions about this





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