I have a 96 850 wagon that has had A/C problems for the last 3 years. Previously I would drive about 15 minutes only to have hot air blowing through the vents and after shutting the A/C off and turning back on, I would have cold air for a short time. I have had a sensor replaced each time to get me through the summer. This year the freon was low and compressor tapping. I had it recharged and now the compressor is not tapping but I have the same problem with the air getting hot after about 15minutes. Should sensors need to be replaced each year?

 

I will bet that the compressor clutch is bad.If you can when it starts blowing warm check for power at the compressor if you have power the clutch is bad.

It would be better to replace the entire compressor.