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Car is at the shop now. The serviced the AC and it blows cold but just doesn't stay on for long time. So cal heat and business trips to LA. I need this on for the summer. Any suggestions?? My mechanic seems to think replacing the AC clutch might do the trick..
 

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Re: Air conditioning stops working after 30 minutes. (p_wadzik)

You've now asked this in 3 forums already, how many more am I going to find?
 

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Re: Air conditioning stops working after 30 minutes. (p_wadzik)

I think you need a new mechanic, and not a new compressor.

The clutch on the compressor is controlled by a switch which determines whether or not there is R134a or R12 (if you're still pushing that sollution around) in the system. Otherwise there is no other override, in most systems, except the controls in the vehicle's interior. So if you're compressor is stopping after 30 minutes of good operation it is because there is a temperature sensor in the interior telling it to stop.

Diagnosing a/c is that hard. Get a gauge with the proper fittings for the type of freon you have in the system. All new cars have R134a and most older ones may have been converted over (look for conversion tag). There is also an a/c tag in the engine compartment informing you of the type of Freon (cooling gas) used by car. If you're a late model Volvo it will be R134a. You can drive into an Autozone and if they're not too busy they hook up a gauge for you. The blue colored connector goes to the low pressure or suction side of the system (where the Freon is in a gaseous) state, and the red connector goes on to the high pressure side of the system where it is in a liquid state. The low pressure side will have the larger hose or pipe attached to it while the high pressure side will have a considerably smaller diameter hose or pipe attached to it.

Afte attaching the gauge, start the engine and put on the a/c. Open the blue fauchet and the red fauchet below the two dial gauges. If the system is operating correctly you will get a reading for the blue low pressure side and the red high pressure side. If the compressor is dead and the guage is working properly and the clutch has engaged (you should either hear a click or else see the center of the flywheel on the a/c compressor turning with the outside pulley ( a white chalk mark accross the face of the compressor's pulley/clutch will aid you in determining if the clutch is engage. The fact that the pulley is moving is non-conclusive because it is always turning. That why it has a clutching mechanism to cut in the compressor and cut it out. Some vehicles have or had a mechanism to cut out the clutch during sever acceleration. I only know my old Volvo 240, my Toyota Corolla, and my Buick Regal. You'll have to seek more information about modern Volvo a/c systems. See your local public library which may have on line access to one of the public auto repair databases or else try alldatadyi.com. You can also query other forums on this site or others or try calling Volvo for info. If you let the car idle for 30 minutes watch the gauge after the a/c cuts out to get a reading on the system. It probably will change and I suspect the a/c clutch will stop also. If you're handy hot wire the a/c clutch to the positive and negative side of the battery using to long sturdy jumpers. This will keep the clutch engaged no matter what (you'll hear a click if the engine isn't on when you make contact with the 12v source indicating the clutch is engaged). Once you've removed the original lead and put the jumpers on, any cut out devise in the system will be negated. Run the car with a/c for 30 or so minutes and check to see if the compressor cuts out on you. If the compressor is still running and you're getting cold air it means you've got a bad sensor somewhere in the system. Get the electical diagram for your car and check it out down wind from the compressor to the on off switch. If the compressor stops working while jumpered then its most likely a switch in the compressor such as the high pressure switch. Most high pressure switches, while costly, can be replaced without having to replace the compressor.
Good Luck...and Keep Rolling.
 
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