my 2005 S40 A/C starts off blowing cold air and with in 5 minutes starts to blow hot air. I do not think this is a problem with refrigerant level or pressure, but could it be that? local parts store doesnt think so and nor do I???? is there a sensor that measures temp in cab? Thanks

 

Sounds like you need a compressor de-shimming. It's called reshimming here but in reality one of the three shims are removed to bring the compressor clutch closer to the compressor. I was able to deshim mine without ever removing the compressor from the engine. Just remove the pass side wheel and plastic wheel liner to expose the compressor.

https://volvoforums.com/forum/volvo-...shimming-6665/

 

Does it happen at idle and start to cool while driving? If so then it's an airflow issue. (make sure condenser fan is working and the condenser is free of dirt and debris. If it happens all the time then you might have a restriction in the system (expansion valve) You'll need a set of manifold gauges to check pressure.

 

What the OP describes is the classic symptoms of the Volvo compressor clutch problem. When the compressor heats up during normal use the compressor clutch expands just enough to cause it to lose grip. The result is warm air as R134a is no longer circulating. When the clutch cools back down it suddenly starts blowing cold air again until the clutch heats up again and the cycle repeats.

The fix is to remove 1 tiny little shim (of 3 total) from the compressor clutch as described in the thread above. When my 2005 started doing this it was only when it was 95+ degrees outside. After removing 1 shim it has worked perfectly.