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Volvo S60 A/C 'randomly' going on and off

Hello Car Talkers!

We have a Volvo S60 and recently the air conditioning has been acting up. Here are some facts related to it:

  • It works 95% of the time.
  • In almost all five instances of failure, we had the car idling for about 10-15 minutes. The AC then died after we started moving, but recovered after another 5-10 minutes.
  • So far we haven’t seen the A/C die when idling has not preceded our drive.

Has anyone experienced this, or does anyone have any ideas before I go to a mechanic and get taken to the cleaners?

It could just be low in refrigerant - they sell cans with a gauge on them that lets you determine whether it is low and also let you put some refrigerant in. It’s gauge usually has a green/orange/red zone. If it is low, just charge it according to the instructions. It could be that simple and cheap. It takes five minutes.
Be careful not to put too much in - that’s actually not good for the system.

Should the pressure according to that gauge be good, look at the compressor:
Notice what it does when you turn the AC on and when you turn it off. When off, there’s a piece that doesn’t turn that does turn when you turn it on.

Next time it doesn’t work, notice that that piece is doing (turning or not turning). That could help diagnose the problem when you bring it someplace.

Great info! I’ll check the refrigerant and post feedback. Thanks for the info!

Usually the AC also has a thermal protection system that can shut it off temporarily if the compressor temp or coolant temp is too high. If one of your electric cooling fans behind the radiator is not coming on as it should when the coolant gets hot during idle, then the computer may be turning off the AC. Then, when you start to drive the car, air is forced through the radiator, cooling it and reducing the coolant temp to the point that the computer allows the AC to turn on again.

You can easily check this by allowing the car to idle for several minutes, with AC on, until the temp gauge reaches its normal operating level. Then verify that both (if there are 2) cooling fans behind the radiator are running. If not, that could be the source of the problem.