1998 V70XC, 99,000 miles. A/C was low on freon and had it replaced (along with dye) a few months ago. It seems to be holding a charge (the evaporator was replaced at 50,000 miles already). The compressor is cycling on and off at a reasonable interval (about 20 or 30 seconds).

In last few days (warm temperatures and constant A/C use), we hear a strange whine/moan/groan/squeak from under dashboard within a few minutes of starting car. It seems to correspond to when the A/C compressor comes on, but when I shut off the A/C (by pushing the A/C "off" button), the noise remains for a few seconds. Also, when I stop the blower fan, it still persists beyond what seems like a reasonable fan-related time (my first inclination was that this was a bad fan bearing).

Finally, when we shut off the car, we hear the sound for a few seconds more, and it almost sounds like the A/C is releasing some pressure (it's is not a blowing sound, but something like a "spooling down" sound). I don't think it is the air pump, because I think I recognize that spooling down sound.

Any suggestions? I will be taking in for 100,000 mile service soon and would like to have a rough idea before I go.

Thanks in advance.