Here is a video that shows how to fix the AC compressor clutch on the Volvo 850, S70, V70, etc. It also explains a few other AC issues.

 

Another great video rspi, quick question, since I've had my 97 850 the clutch engages and disengages every couple seconds, around 30 sec, engages for about 10-15 sec then disengages. This happens while I'm idiling without my AC on. Is this normal?

 

When you say the AC is "Off", what have you done to turn it off. Do you have the AC switch itself in it's Off position ??

If your AC is "Off" then it shouldn't be running. BUT, if you have it in defrost then the AC is supposed to be running.

What will determine if it cycles is that it's reaching it's high or low pressure limits while properly charged and the switches are turning it off and then back on when the pressure changes, it's low on freon and it's hitting that low pressure switch's set point to shut down or the clutch air gap is too wide and the clutch's electromagnet can't hold the clutch.

Have you attached a gauge to see where your low pressure is while it's running ??

 

+1 with the Prince. If the system is low on freon, it will cycle a lot. Usually a clutch problem will cause it to stay off for a long time.