AC woes

This is about the AC on my ’66 Studebaker, but much will apply to the Chevy systems.

My AC started to squeal when it was engaged and then stop when to compressor cycle stopped. That was bad enough, then the compressor started to cycle on and off rapidly. I have a period evaporator in the car with a modern Sanden compressor with R134A.

The Sanden website suggested that the problem might be in the evaporator temperature control switch (This switch isn’t part of the Chevy’s system). Fortunately I have another switch available. Unfortunately it didn’t make any difference.

Going over the wiring I realized that the power to the compressor passed through the low pressure safety switch located at the top of the dryer. When I jumped the safety switch connectors the problem of the off/on cycling went away. I won’t bother to replace the switch as I will need to empty the system of gas and do a recharge. I’ll do that a bit later. I’ll watch the system and if the cooling drops off I’ll check the system to make sure there is enough gas in the works.

The squealing problem is still present. I installed a 12 volt relay temporarily in the system to see if the compressor clutch was not getting its full 12 volts. That wasn’t a problem. I happened to run a feeler gauge between the clutch face and the body. What came out was a thin coating of grease – the upper photo shows the grease on the feelers and the middle with the feelers cleaned. The bottom is a shot of a cotton rag I was able to stuff between the clutch face and body. There shouldn’t be any grease in that area at all. On the next test drive the squeal was present, but the tone had changed and it wasn’t as consistent as before. I’m thinking I’m on to something here. I’ve sent away for a tool kit to remove the clutch from the compressor so I can check out the situation inside. Might be a compressor seal leak. We’ll see after I get the kit and pull things apart.

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