Question1996 Jeep Grand Cherokee 6-cylinder 4.0
Problem:
1. AC system will not take Freon
2. Compressor clutch continuously cycles on/off… on for 2-3 seconds, then off for 6 seconds.
Actions taken:
1. Replaced all AC components except compressor and AC switches
a. Condenser, Evaporator Core, Accumulator w/hose, Liquid line w/orifice tube, Radiator and water hoses
2. Evacuated system for 30-45 minutes
3. System maintaining pressure with no leaks
4. Attempted to charge system; confirmed discharge nozzle pin has pierced can and is in discharge position, left can connected for up to 30 minutes (tried this several times)
5. Discharged system, evacuated, and tried to charge again with same results
Pressure Gauge Readings (PSI)
Engine Off
• Lo = 110
• Hi = 97
Engine On
• Lo = 33-75 (pressure rises and falls as clutch cycles)
• Hi = 100-150 (pressure rises and falls as clutch cycles)
Tests performed using the Factory Service Guide
1. Clutch Cycling Switch – passed test
a. Clutch engages and turns compressor continuously when shorted. Also liquid line does a rapid freeze when shorted.
2. Hi Pressure Cut-off switch – passed test
a. The switch definitely has continuity above 40 PSI, but could not determine if no continuity under 40 PSI, because of the clutch cycling. May not be an issue since I believe I bypass the switch when I short the clutch cycling switch.
3. Compressor clutch relay – passed test
a. Tested with and without power.
4. Confirmed condenser/radiator fan engages and is working
I think the problem may be that the compressor is not providing enough suction and needs to be replaced. However, I may be missing something and would like to get some opinions.
AnswerHI Ken
I like it when you give me information. Did you charge system while engine was running and system on. How much refringent did you put in and when you bypass the cycling switch what are your pressures. I suspect that you are low on refrigerant. By pass switch and add refrigerant. Get the low side to stay between 35 and 45 PSI and the high should be between 200 and 250 PSI. If you high side goes up while charging and the goes below 150 PSI when you stop charging then you have a blockage at the orifice tube. Let me know and I'll help.
