Subject: False A/C Compressor Seizure - Vehicles Subjected to Extended Storage
Model and Year: 1968 - 1982 Corvette
Source: Chevrolet Service News
Page Number: 1
Date: April 1972 - Volume 44 - Number 44
Slipping or broken air conditioning drive belts and/or scored clutch surfaces may be experienced on initial start up of an air conditioning compressor after an extended period of storage or non-operation of the compressor. This would indicate a seized compressor, however an overhaul or replacement of the compressor may not be necessary.
During extended periods of non-operation, changes in temperature cause the freon in the air conditioning compressor to expand and contract. During this movement, lubricating oil carried by the freon tends to migrate from highly polished surfaces in the compressor such as the ball seats and wobble plate. Without lubricating oil at these polished surfaces, they "wring" together and appear to be seized.
Before the time and expense of an overhaul is invested, use the following check to determine if the compressor is actually seized. With a wrench on the compressor shaft lock nut or a spanner wrench (J-9403) on the clutch drive plate, "rock" the shaft back and forth a few times. This should be sufficient to return lubricating oil to the "wrung" surfaces and allow the compressor shaft to be turned by hand. Once the compressor is broken loose, rotate the compressor at least three complete turns. Start the engine and operate the compressor for a minimum of one minute.
This procedure will not affect a compressor that is actually seized but should be attempted before overhauling a compressor known to be idle for a month or longer.
Article ID: 949
Created: October 8, 2014
Last Updated: October 8, 2014
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