Hi guys,
I need help. I will try to explain what is going on but it's weird.
My civic ac runs fine until I turn my headlights on. As soon as I do, the AC turns off. Then I discovered a wire that is connected to the fan control switch pin connector (green cable) and runs all the way to the AC compressor. I am not 100% positive it goes right into the AC compressor but it's somewhere there. Any ideas why this is done to my car and how can i fix it? It's very hard hard to drive like that especially when it's raining.

Thank you all in advance.

 

Has there been any recent work done to the vehicle? When did this start happening? Was it progressive or did it just all of the sudden start doing this? It sounds like possibly the idle isn't adjusting for a load and the PCM is shutting off the A/C to prevent the car from stalling. What is your idle like? That wire I'm not real sure about. What color is it? Are there any aftermarket gauges or anything of the sort installed on your car?

 

Deleted- our resident expert is on it.

 

Thanks for your help guys,
Honestly, I have no idea what they were trying to do but this is annoying. Every time it's raining or just gets dark I have no AC because I need to use my lights. What should I do to fix this? BTW, can I upload some pictures here in this forum so you can check out what really they did.

Thank you

 

I have no idea if any work has been done to this vehicle. It look like this car has been involved in a minor accident. This is actually the only thing that does not work in this car. Unfortunately, I cannot answer most of your questions but all I can do is take a picture so you can see what I mean if that is possible.
Thank you very much.

 

Please do. That will give me a little better information to help you.

 

Also, you say when you turn on the headlights the a/c turns off. Is it just the a/c that turns off or does the fan quit blowing air all together?

 

It sounds like you have a ground problem. Looking at the wiring diagram the headlights and the blower motor share a ground along with a few other items. Look closely at ground 201 behind the right side of the front bumper under the right headlight. There is a 1 pin brown connector near the ground (it's for a fog light so if you don't have fog lights it won't be hooked to anything), and also near the ground is an impact sensor mounted to the frame with a 2pin yellow connector. Make sure it is tight, remove the ground and sand the mating surface with a light grit sand papern (200 grit will be good). If it's been in a collision there is a good possiblity that someone's painted it. I've seen many times body shops paint over grounds and cause all kinds of crazy problems. Let me know what you find.

 

Justin, thank you very much for your help. I will take some pictures today so you can get a better idea. Actually, the main problem is that when I turn on the lights, the AC quits. I can hear the compressor ticking. As soon as I turn off the lights the AC comes back on. The fan does not stop. I will show you in a little bit.
Thanks

 

Okay, I took some pictures and I also made a video explaining the problem.

https://picasaweb.google.com/1018975...eat=directlink

You gonna see a short info underneath the pictures.

The video is still uploading to youtube. I will reply to you with the video link shortly.
Thanks for your time again.

 

Deleted

 

Well, I am sorry about the confusion but It's my first time I have to explain something I am not familiar with. What should I do now?

 

Deleted

 

i was going to respond to this thread last night but i forgot to

like the guy above me said put the wiring back to factory and then test and see whats going on, if it works then the headlights are sucking the ground up. That is a very very haggard wiring job that someone did and it should not stay like that.

also the evap temp sensor, if you are getting a skewed signal there the whole system will not engage at all that is a major input on that system or any a/c system for that matter

 

Thank you guys. I will put all the wires together and check the result.
I will get back to you soon.

 

I don't have multi-meter right now, but I can borrow one tomorrow.

 

Deleted

 

I did it but the AC won't start at all. I guess that is the reason why they run this cable all the way to the fan switch. I am gonna have a multi-meter tomorrow morning. Please let me know what to do.
Thanks

 

Deleted 'cause apparently you don't need to test the fuse, relay, or back-probe the relay socket.

 

I don't know how to thank you enough. I will do everything as soon as i have the multi-meter in the morning. Will get back to you with more info.

 

Sorry I didn't get back with you until now, it's been a crazy weekend. I've been working on Honda cars a while and personally I've never seen a failed Evap temp sensor (not to say it hasn't happened). Where is that Yellow wire under the hood hooked to? I'm looking at the wiring diagram and don't see a solid yellow wire. Do all your fan speed settings work (example low, medium, high)? When the fan and a/c switch is set to on do the condensor and radiator fans run? Also, when the compressor was working did the a/c cool well? Now that I've seen the video @runway6 posted I have a little better idea what's going on. Now that you have the wiring back to factory, here is what I would do:

Please answer the above questions before you do any of these checks.
1). You know fuse 14 is good otherwise the compressor wouldn't turn on. So, testing it is not needed.

2).Go to the a/c pressure switch which is installed on top of the receiver drier under the hood. There is a 2 pin connector with a red wire and a blue wire. With the engine running and the a/c switched to off back probe the pressure switch blue wire, you should have ground (close to 0.00volts), with a/c switch off you should have battery voltage (13.5-14.5volts with engine running). Let me know your findings.

3). Next as a "quick and dirty" check of the relay I would just swap a similar relay with the compressor relay to see if the makes the compressor come on. For technical purposes it's not the correct way to test but for your case it will be just fine.

4). If that doesn't turn the system on, I would the go to the ECM and check if it's grounding the compressor clutch relay.

 

Hi, the yellow wire not suppose to be there. That's the wire that comes from the fan control switch (inside the car). For some reason inside is a black wire, but outside turns into a yellow wire. I followed the cable very carefully and I am sure this is the correct one. It's hooked up to the Blue wire that goes to the AC compressor or AC pressure switch (I am not sure). Have you checked the pictures I posted yesterday? I am not 100% positive but I think fan speed work properly. I don't really have another civic like mine so I can compare. AC is cooling very well.

I just got the multimeter and I am going to follow the procedure LAZONG posted for me and I will let you guys now about the results very soon.

 

All that testing shouldn't be necessary. All he's asking you to do is test the fuse to make sure it isn't open. Just pull the fuse out and look at it. If the metallic interior of the fuse is separated then the put another fuse in and make sure it doesn't blow again. Another thing, Fuse 1 (20amp) also feeds power to the condenser fan relay so if the condenser fan runs you've eliminated Fuse 1 (20amp) as a problem! Swap the compressor relay with the relay to the left of it, and check to see if the compressor turns on, if so then the relay is the problem. I HIGHLY doubt you have a bad fuse box. One good thing about working on one brand of vehicle all day everyday is you see common failures, and that isn't one of them. It's possible.... just not probable. By fan speed settings I mean does the air coming from the vents change (come out faster or slower) when you adjust the fan ****? Do the things I've asked and I promise I can help you fix your car. Fairly simple diagnostics. Keep me posted.

 

I did everything you guys asked me to! Here are the results:

Fuse 1 -OK
Relay - I swapped and also tested the relay - OK
Back-probe relay socket - OK

The compressor won't turn on!

The fan speed works, it definitely goes from slow to fast as I move the ****. However, I think this fan cannot reach its highest capacity. I mean my other car fan blows 3 times stronger on MAX than this one. It's just my opinion, I might be wrong.

I could not do that:
Can you please give me more info where to find it and what to do. Sorry but I am totally unfamiliar with these things. If I am not wrong the yellow cable that you asked me about its hooked up right into the BLUE cable on the 2 pin connector.
Thanks

 

Ok my friend. You've swapped relays and nothing. I was hoping it would be that simple, but no worries. This may get a bit trickier. I'm thinking that you have one of two things going on; either the heater control panel isn't grounding the a/c on input or the ECM isn't grounding the a/c compressor relay. Do both the outside fans (condenser fan and radiator fan) run when you push the a/c switch on and have the fan speed set to a position other than off? Let me know.

1). Also check the voltage on that blue wire at the heater control panel with everything switched to on and let me know what you have. That yellow wire I now know is a communication line between the ECM and the heater control panel.

2).One other important thing I need you to do is take that yellow wire and jump it to ground to see if the compressor turns on. If the compressor turns on then we need to look deeper into the a/c switch, multiplex unit and the heater panel. By jumping that yellow wire to ground we're bypassing the a/c pressure switch, multiplex unit, and heater control panel.

3). If it still doesn't turn on when you ground that yellow wire let me know so that we can start checking the ECM ground for the compressor relay.