I already posted this in the general civic talk forum, but got no responce, so I thought I'd try here. 2003 Civic LX,A fewweeks ago the ac was blowing nice and cold when all of a sudden it stopped working. The AC dash light was still on but the air wasn't cold. I checked to see if the compressor was running, and found that it wasn't. So, I continued on my way and 5 mins later, it started working again. The same thing happened a few days later, and from there it was pretty much every day. I wasn't too worried as it would always come back on after a while. About a week ago, it didn't come back on and hasn't been on since. So the other day I figured I'd see if I could get her going again. The first thing I did was checked all the fuses and relays that I could find, but they were all ok. I then jumped the compressor relay and the compressor came on and blew cold air right away. I then put the relay back in and checked to see if there was power to the low pressure switch, and there was, but only about 4v. At that point I went and turned the blower fan to hi just to see if that did anything. Now I wasn't getting any voltage at the switcheven after trying every speed on the fan dial. So now I really don't know what to do. Could it be the AC button itself or the fan speed control? How could I test that? It seems that the system is fine, but the signal isn't getting from the dash button to the relays to turn everything on. Any ideas on what I should try next would be really appreciated!

 

ok, so I bought a Haynes manual and was looking at the electrical schematics in the back of the book. It looks like the signal goes to the evaporator temperature sensor first so I thought I should start there and see if there's power before and after the sensor. Does anyone know where this thing is and how I can get to it to test it?
-Thanks

 

Woah, thats a lot of electrical stuff, it doesnt show in the book where it is at?

 

no, all it shows is how to take out the whole system and then you can take out the evaporator and I'm guessing the sensor wouldn't be too hard to find at that point. I would rather not take the whole dash apart to test this thing if at all possible. I was hoping someone out there had the actual Honda Civic shop manual and could fire me off a few pages on this or at least tell me what the book says. I'm not even sure if I'm testing the right thing but I have to start somewhere. I'm open to any and all other ideas on this.

 

A common a/c problem with these cars is a faulty thermal protector that sits on top of the pump under a metal retainer, you'll see the two red wires. The wiring comes down from the right-side of the rad to this thermal protector which in turn engages the clutch on the compressor. When I tested mine I had power on one wire but not the other. Some people by-pass this unit when it fails but I wouldn't recommed it since it is designed to fail open to protect your compressor. The part cost me $50 at the dealer. You have to move the power steering pump and alternator aside to get at it though. Remove the metal retainer and gently pry the thermal protector out of the pump. Put a blob of silicone on the new unit and put it in the pump.

 

I can jump the compressor relay and the compressor starts up so, could it still be the thermal protector? If so how would I test it? BTW I'm getting about 4.8 volts at the pressure switch, it that the correct voltage?

 

Get yourself a test light to check the wires on the thermal protector(T.P.). You'll see the wires and connector running along the right side of the rad going down to the unit. If there is no power on those wires with the a/c turned on then the problem is the T.P.. Before tackling it myself I checked with a Honda tech and was told this is a very common problem with the Civic's.

 

Thanks, I'll test it out tomorrow. How hard is it to move the power steering pump and alternator to get to the compressor? You don't have to take them right out do you?

 

Well, I've tested the wires and there is power going to them, so I really don't know what to do next. I think next week I'll take it in to Honda and see what they say. It's $69.95, but at least I'll know what's wrong with it.

 

If you have a single wire going to the compressor/TP assembly, and there is power on that wire but the compressor doesn't engage, the problem is either the TP or the clutch on the compressor. The next thing to check would be to use an ohm meter to see if there is continuity thru the TP and clutch coil (TP: close to zero ohms, coil 3 or 4 ohms). If there is, with the engine OFF, jump the wire to the battery (+) and then if the clutch doesn't pull in, push the clutch plate towerd the pulley (remember: engine OFF). If it then pulls in, you just need to take the plate off and take some of the shims out so the gap is smaller. Also loosen the compressor mounting bolts and check for corrosion that could be causing the compressor to be ungrounded. These are also common problems with a zero-dollar solution.

The dealer will probably only want to replace the compressor/TP as a unit, which will cost you a bomb.