<--- Check my sig underneath my aviatar
I have under my belt so far: basic maintenance, Suspension & Steering, Brakes, and A/C.
If your compressor is not engaging it can be for a number of reasons:
1) Low refrigerant = not enough pressure, and a sensor detects this so it won't turn on
2) Shorted wire to compressor clutch
3) RPM sensor (safety sensor to prevent belt lock up in case the clutch seizes over and locks up)
4) Problematic cycling switch
5) Control head electrical problem
etc...list goes on
more than likely, you got a leak somewhere, you have low refrigerant, your clutch won't engage as a result of low refrigerant, the supposed "cold" air you feel, is simply vent air. A complete remanf. Nippondenso compressor (including clutch) is about $250-$300, if you look around, I buy my parts from
this website and they have held up quite nicely. If they are going to open up your system to fix a leak...and they recommend changing the reciever-dryer, do it, that dessicant can only hold so much moisture from air, until it goes bad, and opening up a system, puts a serious load on there.