I'm trying to troubleshoot my air conditioning problem before handing over my car (and wallet) to the Volvo dealer.

My a/c just shuts off after a while of cooling and working perfectly, and will then start up again randomly, and then shut off again. I have read about Volvo compressors clutch problems, but was hoping this might be something else, and hopefully less costly.

My question is, when the a/c randomly shuts off , why would my heater lose functionality as well?

As soon as my a/c shut down, I tried the heater. After turning the temperature contol dials to hot (with the a/c light off), the heater blower does not engage. The heater will come on when the A/C is working. I don't seem to have these problems in the winter, when the heat works fine (although I don't use it much in Phoenix).

One more note... I did have problems with the a/c only coming out of certain vents a year our two ago.

Does this rule out the comprssor? Any suggestions or thoughts on what to check next? A relay?

Thank you very much for your help.

Marc
2001 Volvo s60

 

The A/C compressor must cycle, and the on/off time will vary with the refrigerant pressure. A system that is low on refrigerant will typically short cycle (engage and disengage at short intervals). An overcharge of refrigerant will usually do the opposite, as the high pressure/low pressure switch will disengage the compressor until the pressure drops to the appropriate level.
To diagnose the system, first check for loss or overage of refrigerant. Next check the air gap at the compressor clutch.

The blower motor should also vary in speed depending on the temperature setting, but should also compensate for changes in user settings and climate. The Relay/Resister module is known to be problematic in these autos.
Vent actuators do fail and become obstructed over time.

 

Thanks for your reply J.A.

Do you happen to know why my heater / blower would stop working when my a/c compressor shuts down?

Thanks!

Marc
2001 volvo s60

 

No, that is a quandary. I do know that when the defrost is on, all other vents are closed, leaving only the defrost vent open (always thought that was a dumb feature).
My guess is the the speed control switch has failed. It is a solid state unit and relatively easy to to replace.