73 eldo covert. Ac compressor

[kkkaiser]

Recently, got ac bk up and running, and was cold.  Today, noted not cold. Cked under hood to see if compressor was working.   While it was engaged, it seemed to be running at about 1/4 of speed of the belt speed.  Is that proper or shpuld i look at further compressor problem

Thanks

[35-709]

Sounds like your belt may be slipping, check it for proper tightness.  After that, check the compressor clutch which may be slipping.

[cadlove]

I would suggest you removed the belts from the a/c compressor and manually turn the rubber front of the compressor. It should turn easily and obviously with no clunking, grinding or obstructions. There should also be no noises coming from the unit.

Then, with the belts back on, check the tensions shown in the workshop manual. You do have a Cadillac workshop manual? If not you need one. Run the engine, turn the Climate Control on and check the sight glass. Earlier '73 Cadillacs have a suction throttle valve and a receiver/dryer mounted near the condenser. The sight glass in these cars is in the receiver/dryer.

Later '73 Cadillacs have VIR (Valve In Receiver) which contains both the suction throttle valve and receiver/dryer. In these cars the sight glass is in the upper side of the VIR unit. There may be a black plastic plug in the hole.

You should be able to see refrigerant passing across the sight glass, sometimes it will frothy. The top of the VIR unit should go cold and in some cases go white with ice. This is a simple way to check if gas in still in your system. It does not check how much gas is it in?

The '73s have a thermal switch that senses heat and with low refrigerant that should blow. These were not perfect? JP

[Daryl Chesterman]

The compressor should run the same speed as your belt—your compressor clutch may be slipping and could be caused by low voltage to the clutch.  With the clutch engaged, you can check the voltage to the clutch to verify that it is getting battery voltage (at least 12.6 volts)
to the clutch coil.  Just back-probe the electrical connector to the clutch coil to check the voltage.

Daryl Chesterman

[TJ Hopland]

With the engine not running how hard or easy is it to turn the compressor by hand?   Every time I have had one not going belt speed it was the beginning of the end for the compressor.