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Tight or Locked-up GM Compressors

We have heard from several technicians about the following two issues with GM style compressors: R4, HR6, HD6, HT6, and V5.

The first issue is at times the compressors are very difficult to turn by hand right out of the box.  These compressors are built with Teflon covered piston rings that are pressed into the pistons slot.  These rings "flex or expand" and create a positive seal in each cylinder.  The answer to the complaint - you need the right tool to free them up.  The tool is called a "Spanner Wrench", and most auto parts stores have these items for sale.

The second issue concerns the compressor "shaft nut".

GM Corp released a TSB (Tech Service Bulletin) number 93-T-03 dated October 1992.  The subject of which is: Compressor Shaft Nut Eliminated, all R4 and H6 series compressors.

   "Effective after July 13, 1992 for the R4 compressor or April 28, 1991 for the HR compressor, the shaft nuts were/are no longer produced for these units.  This affects both production and service compressors.  The elimination of this nut has been made possible by improvements in the clutch driver to compressor shaft press fit.  If you receive an air conditioned vehicle with an R4 or HR compressor and there is not compressor shaft nut present, no attempt should be made to install a nut."

We will keep you posted as new TSB's come out.