1996 XJ Sport, 4.0

Yesterday while traveling around 50 MPH steady-state I noticed an increased temperature output through my vents. It gradually increased over the 10 miles from work to home and was just barely below ambient temp (Florida). Once at home I attempted to service the system with refrigerant, thinking a leak had possibly occurred, and perhaps a shot of refrigerant would act as a troubleshooting method. If the temp dropped significantly then the compressor was at least performing. But, the low side would not take the charge. It maxed out the gauge and I disconnected immediately. Oil discharged from the fitting as I connected/disconnected the service fitting and it was clean with no hint of discoloration or odor from a burned up compressor. The compressor clutch was cycling as I switched from vent to AC and back, and remained engaged while in the AC mode. That was last evening.

This morning I expected a mildly sweaty trip to work but the system started operating normally and remained steady for the 10 miles to work. I understand there's a low pressure switch in the system in circuit with the clutch but the clutch was engaged and the low pressure side seemed to be amply charged. I'm not an AC guy. I'll take it to the last service company I used and find out what's what. Has anyone experienced this kind of performance from their AC systems? The fix?

Thanks,

 

Generally this is a symptom of being slightly undercharged. When charging, you hold the can upside down and slowly add liquid to the low side while the compressor is running. Being slightly low allows the evap coil to get too cold and freeze up, at which point it fails to cool air much. The low temp safety switch will not allow the compressor to engage and high side switch disconnects power to the compressor if the pressure/temp on that side is too high.