Quoted From spelunkerd:
So, if I am reading you correctly, low side pressure rises when compressor starts, high side doesn’t change. Would it be possible to have accidentally hooked the new compressor up backwards?
I’m on this same train of thought. I’m not sure if it’s possible to hook the compressor up backwards, but if so, then that makes perfect sense. Otherwise, make sure you have your gages on the right ports. If it’s an R-12 system, then the connectors are identical. It’s more likely that the high side is getting high fast, and the low side is getting nothing. This could be due to a clogged metering device (orifice tube, thermal expansion valve) and the high and/or low side pressure sensors aren’t seeing what they want to see, and that’s shutting off the compressor.