1988 winnebago superchief AC question

[SEEJAYFDL]

When I turn on the dash ac the belt squeals. It's like the clutch is not engaging all the way so it is hard to turn. My question is could this happen because the R12 freon is low or is the clutch bad? The belt is tight.
Vehicle info:
1988 Winnebago Superchief
Chevy P30 Chassis
chevy 454 7.4L engine.

Thank you

[GM Tech]

If compressor is tight to turn by hand and belt is tight-- look out - it is seizing- as in locking up prpobably due to lack of lube from running on too low a refrigerant charge. Refrigerant oil does not travel well with loss of refrigerant- and can cause internal compressor damage. If compressor turns easily by hand, then tighten the belt.

[SEEJAYFDL]

It turns by hand and the belt is tight. The belt slips and squeals when ac is turned on. It looks like the clutch only partially engages when ac is turned on and then the belt slips because it stops turning freely. Hope this makes sense. Thanks

[Jag987]

does it easily turn by hand? Like with just a couple of fingers or does it take a bit of work to turn it?

[SEEJAYFDL]

Takes a bit of work.

[SEEJAYFDL]

If I replace the compressor (A/C Compressor 4 Seasons 57552) and use R134a adapters on the low and high side ports could I fill it with R134a freon. Both ports are on the fittings that hook up to the back of the compressor on the suction and discharge spots.