I just got done with a valve cover gasket job and took the car out for a spin ('04 Disco), and everything seemed normal except that there was no A/C. The A/C had been pretty weak before I did this job – I believe it needs refrigerant, but there could be something deeper wrong with it – but it's now blowing warm-ish air at the lowest temp setting. I drove it for about 30 minutes and didn't notice any issues other than this. I looked under the hood and the A/C compressor pulley was moving, though I'm not sure this means anything. The fan was blowing and coolant reservoir levels were normal. I didn't see any evaporated water coming from the bottom of the car, naturally.

Is there anything I could have done changing the valve cover gaskets that would have affected the A/C? Anything I should check? I did remove a metallic covering from one of the A/C lines that was already falling off, but I can't imagine this would have any effect. Should I press on one of the A/C valves to see if the system has any pressure?

Edit: I checked the A/C valves (high and low sides) and it seems to have pressure about an hour after being driven. I don't know if it's full pressure, of course, but perhaps this narrows it down. I should say I don't know much about A/C repairs outside of what's in the RAVE manual. The rear A/C is also blowing hot air, which to me suggests it's not a compressor issue (the rear A/C has a separate compressor, so if the main one was faulty in theory the rear one should still work providing there's refrigerant).

 

Check to make sure that the clutch is engaging. Turn on the defroster and the center of the A/C pulley should rotate.

If it doesn't, the most likely cause is low R-134a.

Did you disconnect the wire form the clutch when you did the valve covers? If so, did you hook it back up?

 

Thanks – I'll give that a shot, looking at the center of the A/C pulley. I did disconnect the A/C compressor unit when I did the valve covers. And I did make sure it was plugged back in. I'll unplug it and plug it back in again just to make sure.

 

Ok, I've checked it out. The A/C clutch is not engaging – the center of the pulley is not turning with the lowest interior temp set, whether I have it on defrost or not.

I checked the fuse, and it's fine. I also disconnected the plug to the compressor, sprayed it with some electrical cleaner and reconnected. Still no response.

What should my next steps be? I'm thinking I need to find out if the compressor is getting a command to start. Should I hook it up to a multimeter and run it?

I also noticed there was a relatively small but still noticeable amount of water dripping from the exhaust when I started it from cold. I'm assuming this is unrelated.

Edit: I will also make sure the refrigerant is topped up, as I've read the computer won't allow the clutch to engage if there's not sufficient refrigerant in the system. May as well eliminate that variable.

 

Well, I took it to a local a/c specialist. They put their gauges on it and quickly determined that there was absolutely no refrigerant in it. After confirming that there weren't any leaks and that it would hold a charge, they recharged it. The clutch immediately started up when they started the engine.

Just goes to show that the clutch isn't going to run if the system's not charged. Luckily a recharge wasn't that expensive.