My 94 940 A/C has not been cool in two years. When I looked at it today after driving home and everything in the engine compartment was hot the compressor would not come on even if I shorted the plug from the pressure switch at the drier ( is there a high pressure switch at the compressor to preventing engagement). After cooling a bit I tried again and this time the compressor engaged on its own and the high pressure line after the expansion tube became noticeably cold and moist with condensation. Vents still blowing 80 with ambient around the same. The pressure at the low side read 40 and increased to 50+ with the compressor constantly engaged. By now the pipe has lost its coolness that was there before. Is this sounding like simply a low 134a condition? Why would it initially seem to be cooling and then seemingly stop by the change in temperature of the pipe after the orifice tube?

Dirk
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Dirk Story