Bought a used 02 Honda Civic. The air conditioner did not work. Compressor and everything is checking out ok so far but this is what I found: in the fuse box under the hood, the compressor clutch relay 4p socket, if I run a ground wire to the #4p the air conditioner works perfectly. So what is the problem? I don't know what to do next. Really need some advice.

 

I could be wrong on this.. but look at this. It's helped MANY people on here

https://honda-tech.com/forums/honda-civic-2001-2005-78/diy-how-fix-ac-power-transistor-2041582/

 

Hey, thanks for the info, and the quick response. I'll give it a try.

 

No prob. It's super easy to do and there has been a high success rate. Let us know how it turns out!

 

That transistor checks out ok, so I don't think that is the problem. Seems like it is a problem with a ground somewhere since I can manually ground that relay switch and it works. Running out of places to look.

 

Interesting. I'm out of ideas for you, but I'll bump it up for more attention. Somebody should be able to set you on the right path here.

 

I think I have the problem narrowed down.... I have no ground from somewhere inside the car to the compressor clutch relay switch in the underhood fuse box. I just don't know how or what to fix.

 

could the ECM/PCM be causing this problem? Is there anyway to check?

 

it could either be your ecm/pcm or the heater control panel and sending the ground signal to the a/c compressor

 

is there any way to test to see which is causing the problem?

 

i am attaching a diagram for the a/c system. at the ecm u need to check connector e18 and at the heater control panel a4 they should both switch to ground when a/c is turned on

 

good **** ^^

I told you somebody would come on here who knows!

 

e18 seems to be the problem. So does that mean I have to change the whole ECM unit?

Also I'm not sure how to test a4?? Can you give directions?

 

yes you would have to. i would rec having the dealer do it.that way u dont have to tow it to the dealer since the immoblizer system needs to be reprogrammed.

to check A4 at the heater control panel you would have to remove to heater control panel and check to see if u have a ground signal when a/c is turned on

 

yes, I will take to Honda shop if it is the ECM unit.

But I would like to test the heater control first. Do I use an ohm meter to test... if reading goes to 0 when a/c is turned on, does that mean it is sending a ground signal?

 

if u use a volt meter it should read 0 volts when you turn the a/c on. if you apply ground at the ecm E18 and a/c works then everyhting from the ecm to the compressor is good replace ecm. whats the mileage of your car??if it under 8/80 it covered under warranty bring it to the dealer have them replace it for free.

 

Thanks for all your help!!!

It's an 02 with a little over 80,000 miles. But it hasn't been working since 70,000. Hope they still cover it.

 

you might get lucky and they will goodwill it for you. do u have an extend warranty

 

no extended warranty, but by 8/80 do you mean 8 years or 80,000 miles, because then it would be less than 8 year old, so should still be covered

 

yes thats what i mean by 8/80. what sucks is warranty is up by which ever comes first

 

took car to the Honda shop today. They think it is the Thermal Limiter on top of the a/c compressor. They are not 100% sure but said they have seen those go bad before and would like to change that first before changing the ECM. Cost me $48 to diagnose. They would have to order the part, $73 for part, $176 for labor. I may try changing that myself .

 

its a little bit of a pain to do i usually evac a/c and remove one of the a/c line replace the part and reinstall line and recharge a/c. its up to you if you wanna try it. good luck keep us posted

 

I didn't think I had to evac the a/c. Do I have to or is that just the way you like to do it? After talking to the tech at the shop he didn't say anything about that. He just said it was a pain to change because you have to take out the alt and p/s to get at it.

I just changed the alt in this car a week ago. Wish I would have known this while I had it all apart.

 

i think you can do it with out evacuating a/c i just do it that way cause i dont remove alt or p/s.

 

Changed the Thermal Limiter today, not too bad of a job. a/c works like a charm now!!