Automotive Air Conditioning Information Forum

... of the compressor.


Chevrolet Service Bulletin
Bulletin Number: 92-35-1D - (10/11/1991)

When using sealing washers, there will be an intentional "gap" between the compressor rear head and the air conditioning hose assembly block (suction discharge block assembly). Do not mistake this as a loose ...

... the compressor and engine. It's possible that the drive belt and/or clutch are slipping. An oily belt or clutch will do that. It's also possible that the gap between the clutch plates is too wide, preventing the compressor from re-engaging. A new compressor or any new part doesn't always mean that ...

... much oil or the wrong type of oil in the system, a slipping magnetic clutch (weak coil or too wide of an air gap), a defective A/C amplifier, or the sensor itself could be bad or ungrounded.

First guess would be a low charge, especially since the low-side pressure drops below 25 PSI, and then the ...

... you should see HS pressures of around 190-210 PSI and vent temperatures of 40-45°F at the aforementioned ambient of 85°F at about 2,000 RPM.

Adding an electric fan and sealing the gap between the condenser and radiator using foam insulation from your local home center probably will help cooling.

... with a parallel-flow type will probably help it some. Also, ensure that air can't get around the condenser instead of going through it. If there's a gap between the condenser and radiator, you can fill it using gray foam insulation from your local home center. Also ensure that all baffles and/or fan ...

... By replacing the compressor assembly, you will eliminate the clutch-gap question as well because it will come with a new, properly gapped clutch already installed.

You should be aware that compressor manufacturers typically require that the condenser be replaced at the same time, along with ...

... to where the compressor won't engage anymore. Either that, or the clutch gap is too wide.

The way I see it, given this truck's age, you have three options before getting into a much bigger and more expensive system overhaul:

One, try to locate the leak(s) via a "sniffer" and partial charge ...

The low side gauge indicates to me at least that you are somewhat low on refrigerant.

While you are at it measure the clutch gap, it s/b no more than .020

... I'm not an AC professional.

I'd like you to measure if the AC clutch is still getting 12 volts positive after the AC clutch disengages. This ... I fixed that (still fixed today) by removing a shim to decrease the air gap; I didn't even need to remove the AC belt to do this, took less than half ...

... One for Manual A/C (scroll compressor, fixed displacement, with a clutch), and another for Automatic Temperature Control (piston compressor, direct drive, no clutch, variable displacement, with an electronic control valve).

You said you checked the clutch gap, so might it have Manual A/C (no ...