The air conditioning stopped working this morning, worked fine last night. Here's the deal, I checked the fuses under the hood and found a blown fuse for the condenser fan, replaced that now the fan works when the a/c is on but still no cold air. I checked the controls, all seems to be working alright there. I can't hear the clutch engaging in the compressor when I hit the a/c switch but the condensor fan comes on. I tried swapping the relays in the engine compartment fuse box and I checked #1, 4, and 12 fuses also under the hood and all are fine. I have a Haynes manual and it shows two under dash relays: Multiplex Control Unit and ECM/PCM does anyone know if these relays are common culprits. Also I see an a/c pressure switch in the wiring diagram. Any ideas as to what to check next?

 

The AC pressure sensors tells the computer to not to engage the clutch if AC system pressure goes too high or too low. First check the pressure on the system, it sounds like you have lost too much refrigant. You can do this with a $30 recharge kit of autozone that comes with the pressure gage. Normal operating pressure on your vehicle is 40psi (lowside). The system takes 5 ouches of oil and I believe 32 ouches of refrigant. (There should be capacity sticker under the hood on radiator support). Pick a kit has leak sealing agents in it in case you have developed leak somewhere. Without knowing the mileage I can't point you to the right direction on trouble shooting the leak location. Typically leaks will develop inside the compressor around 120k miles depending on how much AC has been used. You can load up the system with UV die which you can detect with UV light quite easily.

Juha

 

Since your clutch is not engaging the first thing you should do is to find out why it is not engaging. You could try and short the connector for the pressure switch, if the refrigerant is the problem then the clutch will engage. Only short the switch for a short time as doing it for an extended period could cause problems with your compressor. If the compressor clutch still does not engage, you have to find out why its not engaging. It could be possible that the relay for the clutch is no good (located in the engine compartment) or that the clutch has burned out. You will need a voltmeter to test the relay and i can find out which wires to check if you need me to.

 

Here is where I am at now: I checked for voltage on the blue/red wire running down to the compressor and I do have voltage there. There is a black and a red wire on top of the compressor, the black wire has voltage but no voltage on the red, is it possible the thermal protector is the problem. I also took the clips from the lower panel in the wheel well to make sure the clutch is free to turn and it was. I'm wondering if the thermal protector was the cause of popping that 20A fuse for the condensor fan. Btw, this car has 204K (mainly highway kms) and I had the pressure checked at a local garage and they told me it was ok.

 

The thermal protection is on the power side of the compressor clutch. Check to see if there is voltage at the blue/red wire that is coming out of the compressor clutch relay, going to the compressor clutch. If there is voltage here, then the problem is either the thermal protection or the clutch. Next find the thermal protector, it has a blue/red wire going to it. If there is no voltage after the thermal protector than the thermal protector is turning off the compressor. I suspect that the thermal protector is using the voltage. I don't know how the black wire has voltage since it is on the ground side. Trace the black wire back and see where it goes. There isn't anything on the ground side of the clutch that should use voltage so maybe that is your problem.

 

Update: a/c working again, it was the thermal protector that sits on top of the compressor. Thank you to everyone who answered my post, I hope this is of benefit to others.

 

Does anyone have any ideas on the issue I've come across. All was fine until I tried recharging. It Initially tested @ 25psi max so I proceeded to refill.




99 civic and I just attempted to purge the system a bit and recharge. PSI on the LOW side is on the correct 25-45 range but now the compressor keeps cycling on and off at high rpms. any advice would be apreciated.

 

hi like to know how did you change the thermal protector?
can you send me step by step how to change the thermal protector for honda civic ex 02?