I refilled the refrigerant in May 2004, and the Golf was cold again until July 2005. I took it to a shop, and they topped off a pound of refrigerant and ran the cold a/c for 45 minutes. It blew cold air for another 30 minutes over the next two days, and then it stopped blowing cold air again. I noticed that it would blow somewhat cold if the weather outside was cool and the blower was on level 3 or 4. They did a free diagnostic and found the high and low pressures to be 60 and 30 psi. They also discharged 1.79 pounds of refrigerant, so it was not leaking. They told me to come back and they would install a new expansion valve and blower motor. It was the end of summer, so I didn't get it done. Now it's May 2006, and I took it to another mechanic. He did the same test, and the pressures were different, but normal- something like 100 and 20. This mechanic suggested replacing the compressor, expansion valve, and dryer.
Is anyone able to explain what exactly is going on? If it's a compressor, aren't there computer codes for that? There are no check engine lights on. Should I take a chance and just replace the expansion valve and refill the refrigerant and go from there?
The "Check engine" light only comes on for emission related things so no the AC will not turn the light on. Also if you have the proper pressures then it's not the compressor. If any air comes out it's not the blower. So what does that leave us? Well turn on the AC and raise the hood. You'll find 2 aluminum lines coming from out of the passenger side of the firewall. See if the larger of the 2 is cold and sweaty. If it is then it's possible the blend door has a problem. Also look for a better shop!
If he claims the pressures are ok, why replace the expansion valve, dryer and compressor since they correlate to correct pressures? If any of the components are bad the pressures will be very screwy after a few minutes of running the AC. Does your blower fan work on position 1 or two? If it works on 3/4 and not 1 and two its the console switch. Ok, now to your AC. When the AC button is engaged do you hear the front radiator fan engage and the compressor kick in? Get a kitchen thermometer and start taking readings - first outside air then from the CENTER vent with recirc closed. On my 95 GTI I get about 38F after about 10 minutes of running with the switch set at postion three. 38F is excellent and it never goes above 42 even at idle with temps in the 90's with very high humidity. If you initially get AC and then the temps start going up you may have blend door foam rot which is pretty common. Also check the recirculator flap that sits in the fan box under the passenger footwell. Feel with you fingers through the mess under the fan - if you feel a door at the mesh the recirc flap is not closed and you are trying to cool hot outside air. This door is vacuum controlled and you may have a vacuum leak somewhere between the firewal and the flap mechanism. The foam rot is impossible to see it since its contained within the heater box. You may see something if you remove the fan and look in the airbox but I doubt it. Basically the blend doors are made out of aluminum and they have holes which are covered complely with foam which breaks down from the heat. Since the doors now look like swiss cheese they will pass the heat from the heater core into the ac airstream turning the air hot. If this is whats going on - you can bypass the heater core from the engine compartment by pulling the heater core hoses and bridging them together. If you get cold air you know its the doors - which are a pain to fix since you have to remove the entire dash to get at the heater core box. If this doesn't solve the problem then you definately have AC problems.
If when running listen with the radio off and the windows down to hear if the compressor kicks out or makes any strange noises. Our AC systems are totally pressure dependent and if the front fans aren't engaging the internal pressure will go up and trip the pressure valve cutting out the AC - a 1/10 of a pound overcharge can sometimes do this. An overcharged system is bad for the compressor seals and you should hear the compressor groan when the revs of the car are increased. You can easily wear out a compressor when its overcharge and you won't get great cooling either. If the compressor is running fine and doesn't kick out it may be just worn but this should have been detected by the AC guy.
Replacing an expansion valve, and dryer with a total system flush and evac is a good idea since the oriface on the valve can get clogged over time. The job isn't all that expensive - however I'd go over the steps above first. I'm curious did you take it to an AC only shop of a general mechanic? An AC specialist would NEVER top off a system - they would do a recovery, vac evac and total fill to get a correct amount of refrig in the system since air can get in during a "top off" which really messes with the system.
Report back - you don't want to pony up for the compressor and bits if you don't have to - its a pretty expensive job and you would kick yourself if it was something simple.
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Yes, the blower works on all levels 1-4. I don't hear anything engaging after I hit the a/c button for the few minutes I have it on. I looked under the hood and felt the line connecting the firewall to the compressor, and it was not sweaty or cold. I had said the a/c seemed to get somewhat cold with cooler weather outside, but this doesn't seem to be happening anymore. I'll have to find a good specialist in the DC area - I wouldn't know what I'm looking for under the dashboard.
thanks, W> If he claims the pressures are ok, why replace the expansion valve, dryer
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