Automotive Air Conditioning Information Forum

Year: 2006
Make: Jeep
Model: Wrangler
Engine Size: 4.0
Refrigerant Type: R-134
Ambient Temp: 78
Country of Origin: United States

Hello everyone, I'm new to the forum and need some help figuring out why I'm having trouble recharging my Jeep's A/C system.

Background. A/C clutch wires got too close to the exhaust manifold and melted. Clutch stopped working. Before I found bad wires thought compressor was bad and had R134a recovered in preparation to replace compressor. After finding wires and fixing them went to charge A/C. Pumped down system for over an hour, let sit for over an hour with no leak down. Went to charge through low side port expecting R134a to be sucked in. instead the Low side gauge showed pressure at 80 psi, no movement of R134a into system, no movement of high side gauge. Had vacuum on high side port, repeated pump down and then attempted to recharge system. Same result as before. Had done some research and attempted to charge system from high side with engine off. this partially worked. high side sucked 3.5 oz, high gauge showed 50 psi, low side still showed 80 psi. Closed high side valve and turned on engine, blower high, A/C on recirculate. Thought low side would draw R134a, but it did not. Gauge stayed at 80 psi and high side fluctuated between 75 psi to 85 psi when compressor kicked in Since I couldn't get R134a to fill through gauge set I pulled low pressure line of and attached canned R134a with its own gauge and fill trigger. That gauge showed pressure at the green/red line with engine off. With engine on gauge needle dropped to zero and rose to just below green zone when compressor kicked in. I attempted to add R134a which worked. I added a little at a time watching the gauge rise from zero to below green zone to where it was in the green zone consistently during compressor cycles. High pressure side rose during the fill to 230 psi with compressor kicked in dropping to 150 psi where the compressor clutch kicked in. Took can off low side port and reattached gauge set to low side connector. Gauge reading was 83 psi. That pressure did not fluctuate as the compressor clutch kicked in and out like the high side pressure did. Compressor clutched cycled about every 10 seconds. I had been weighing R134a as I charged and added 20.04 oz by weight. That puts system .04 oz over spec which is 20 oz. Ambient air temp was 78 degrees, 52 degrees measured at vent. With the engine off the gauges showed 83 psi on low side and 62 psi on high side. Small line from compressor to condenser was hot after running system and lines from condensor to dryer then evaporator were cold and sweating. Research doesn't really seem to fit my problem since low side gauge needle doesn't move. Any help or thoughts would be appreciated. Thanks

Updated information. overnight the A/C system has equalized to 72psi low side and 72 psi high side

Your low side coupler is not working to open the valve in the car, so there is no way for refrigerant to flow to charge or to get a valid pressure reading. This often happens with one particular brand of cheap tools.

When you start from an empty system, always charge by weight. If you charged to the proper weight and the air is cold, the job is done; put the plastic caps on, close the hood and walk away.

New twist on my recharge problem. I took MK378s advise and closed hood, drove car for a day and out of curiosity checked low/high pressures. Low side was at 72psi (engine off or on), but high side had dropped to 100psi and rose to 150psi when clutch cycled. Evacuated system, pulled vacuum, vacuum held. I removed the low side Schrader valve rehooked low side hose, pulled vacuum again, vacuum held, tried to add R134a to low side, pressure jumped to 72psi but no R134a flowed (engine off or on). Engine off, added R134a to high side - it took a little -, high pressure went to 50psi, no change to low side. Evacuated system and found that system would only evacuate from the high side port. When I closed the high side valve there was no flow, when I opened it R134a flowed and eventually evacuated. Pulled vacuum which has held overnight. Think I must have a one way block somewhere in system, but not sure. Any thoughts would be welcomed before I start pulling components. Thanks.

Just like mk378 stated, your low side Schrader valve isn't being open by your coupler. The 72psi is just what flowed from the refrigerant tank up to the low side Schrader valve. My gauge set couplers have a built in on/off valve so I won't run into that problem.

Are you sure your's aren't adjustable like mine? If not check to see if the coupler has a adjustable depressor pin like some brands of hoses or not?