<VV> A/C Compressor ...Quasi Vair

Frank DuVal corvairduval at cox.net
Thu Aug 10 22:42:11 EDT 2006


Now all the automotive A/C tool suppliers sell the rotary vane vacuum 
pumps, but 20 years ago they were very expensive, so most vacuum pumps 
one bought for automotive A/C service were hermetically sealed 
compressors. They will pull a good vacuum, say better than 28 in hg. 
There is a guy selling plans on ebay (220015320097) to build a vacuum 
pump from a compressor that shows a 30" hg gage reading (must have been 
a high barometric pressure day). Of couse you can save your money 
because my earlier e-mail gave you the instructions for free (just short 
on details, but e-mail me). The internals of the hermetically sealed 
compressor are not designed to seal to 15 microns, but it is better than 
those air to vacuum pumps sold to automotive shops (Snap-On being one 
supplier), just a rotary vane is best, but costs money.

The A/C compressor in the car may be designed to run 25 to 45 psig, but 
close the suction hose with pliers and see how much vacuum it will pull!

Frank DuVal

FrankCB at aol.com wrote:

>     All good points, except that I would be surprised if a 
> refrigerator compressor could "pull" a deep enough vacuum to remove 
> nearly all the air from an A/C system.  After all, a regular A/C 
> compressor in a car is only designed to work with suction side 
> pressure of 25 to 45 psiG, so it seems unlikely that it could get 
> close to 0 psiA (MINUS 14.7 psiG)
>  
>


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