We have a 1998 Cherokee with a tempermental A/C system. It seems the clutch doesn't engage even when the wire to it is hot. I'm used to working on Fords where the low pressure switch is in parallel with the clutch so that if the refrigerant is low, it shuts off the compressor. However, this clutch will sometimes not engage when the wire to the coil is hot. It seems to most often happen when the ambient temperature is high (>90F). When the clutch is engaged, it seems to cool just fine.
I took it into a local wrench, and they claimed it was low on refrigerant and added about 1.5 lbs. This fixed the problem for a couple of days, but it went back to its same tempermentalness. I have not taken it in yet. I have old A/C gauges that are not set up for R-134.
Any advice on these things? Is there an internal swith in the compressor that will shut off the clutch at low pressure?