Strange noise when A/C is on in my '90 Accord

When I turn the A/C on in my '90 Accord 4-cylinder LX sedan, it makes a loud whining noise. When I turn it off, the noise goes away. The car drives just fine with the A/C on. I assume this is something with the A/C compressor. Anyone know exactly what it is and what is involved in fixing it? Thanks in advance!

If it's the compressor (which it sounds like it might well be) then the only fix is a new compressor. Not cheap. Does the AC work? If it does, you might as well keep driving until it gives up altogether.

Yes, the A/C works just fine. I had to give it a charge several months ago because I was nearly out, but since then, it gets good and cold.

The whining could be a loose belt or even an overcharged system putting an extra strain on the belt system.

The whining could be a loose belt or even an overcharged system putting an extra strain on the belt system.

On the compressor? I have taken the car to a local Honda/Acura repair shop that specializes in only these makes of cars and they are very good with their work. I'm guessing I should take it to them? I don't want to get charged an arm and a leg for this.

Spray a little water or WD-40 on the A/C belt while it's running with the A/C on, and see if the noise changes or goes away. If it does, you just have a loose or glazed belt that's singing.

Thanks., I'll give that a try. To add, it doesn't do this all the time. Particularly when the car is sitting idle at a light with the A/C on full blast. Once I start to move, the noise gets a bit louder then goes away completely.