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.

NEW INFORMATION:

Tried shutting off the A/C switch and leaving it off during a 1/2 hour ride. The noise persisted for a few seconds (its dying gasps?) and then was quiet for the remainder of the ride. The climate control fan continued to run during this period.

So... it seems like it is something in the A/C compressor. When it fails, can it make a moaning/low-pitched whining sound? Does that mean it has to be replaced?

All help appreciated.

Sounds like it could be either the air-pump or it could be your auxilary cooling fan that comes on with A/C? Easy way to rule out the air pump is when you first start the car in the morning, back it out say 50-60 feet and the air pump will kick on....stop car and get out and listem to it to see if its makking any wacky noises.