How to diagnose warm A/C?
 

I bought an '02 Civic EX a few months ago and the A/C has never been cold. Could anyone give me any advice on what sort of things I can check to try and diagnose why the A/C is not cold?

Really the only thing I've tried so far is turning the A/C on full blast and while driving 65+ on the highway, which is something I read on this forum, but it was still not cold.

Thanks for your advice :)

Re: How to diagnose warm A/C?
 

I'd get yourself the professional 134a a/c guage set from harbor freight tools or a friend with one and check your high/low side pressures... See if theres freon in there, if there is and its not working, check all relays,fuses, etc... Could be a few things that are wrong, most likely its the a/c compressor in the end usually, what kinda miles are on the car...

Re: How to diagnose warm A/C?
 

well two thing that are fairly obvious but good places to start....

- is the a/c fan coming on when you turn the a/c on?

- is the compressor turning on/cycling when you turn the a/c on?

Re: How to diagnose warm A/C?
 

I'll look into that, thanks.

Are you talking about the radiator fan? If so, it comes on often, but I haven't paid enough attention to notice if it comes on specifically when I turn the air on.

I'm not quite sure what you mean here.. The compressor is hooked up to the crankshaft via a belt, so it always turns, right?

Re: How to diagnose warm A/C?
 

Make sure its not out of freon. My AC all of a sudden went warm one day last summer so I got it checked and it was fine but the freon was all gone so i had it recharged.

But when you recharge it you need to have your entire system cleaned and flushed through all the lines, from what I was told, THEN refill with new freon.

But the dumbass who did mine just refilled it, didnt bother flushing out the system so even though my AC is cold, its probably not as cold as it could be.

Re: How to diagnose warm A/C?
 

start the engine and open the hood with a/c turned off....now get somebody else to turn the a/c on while you watch the fan, it should come on as soon as the a/c is turned on....does it?

the compressor pulley is "free spinning" when the a/c is off, the compressor is not turning, it basically has a built in clutch....

again, start the engine with the a/c off and open the hood.....have somebody else turn the a/c on while you watch the compressor....use a bright flashlight so you can see the side of the pulley good.....when the a/c is turned on you should hear a "click" from the compressor and you should see the side of the pulley start to turn....does it?

Re: How to diagnose warm A/C?
 

Thanks for your help.

I tried doing as you suggested (but by myself, since I don't have anyone who can help me at the moment) and the radiator fans did not come on when I pressed the AC button (the LED light on the button did come on when I pressed it). I tried looking at the compressor before and after, but I was unable to determine whether it was engaged or not. Also, I did not hear a "click" when I pressed the AC button, and the RPMs did not change at all.

Re: How to diagnose warm A/C?
 

I just read in a guide where to find the A/C Compressor Clutch Relay and after swapping the horn and A/C Compressor Clutch Relay the horn still works, so I guess the A/C Compressor Clutch Relay is not the problem.

EDIT: I found this guide and everything is OK up to step 12, I'm trying to find the ECM now :)

Re: How to diagnose warm A/C?
 

from what you are saying here i think your problem is most likely beyond the capabilities of most home mechanics, i think it would be best to take it to a shop that specializes in a/c work....hopefully it is just a leak somewhere and not your compressor itself

Re: How to diagnose warm A/C?
 

You are obviously in above your abilities.
Take it to a shop before you cost yourself more money in mistakes.

Re: How to diagnose warm A/C?
 

Agreed.



It probably won't be the PCM. It is almost never the PCM. The PCM datalist can be checked and ruled out by a competent tech, in a matter of several minutes in most cases.

Re: How to diagnose warm A/C?
 

OK, thanks for your advice everyone. I was hoping that it would be an easy repair I could make myself, but I guess I'll just break down and take it to a shop :rolleyes: