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low pressure switch for r134 = DORMAN 904625I am converting my 1990 GMT400 from r12 to 134a. Does anyone have the part numbers for the pressure switches of the r4 compressor and dryer?
Thanks,
Rick
Yeah the earlier R12 systems used a 1 wire HP switch, which is NLA. GM designed it to close the recirc door, when you get high pressure, to help bring it down. Remember R12 ran lower pressures. On my 88, I wired this HP switch in series with the LP Cycling Switch so I have protection against HP blow outs etc.My 1991 only has a relief valve on the compressor instead of a high pressure switch.