spohner

Hey Guys,

This last week I replaced the evaporator on my 1994 Jeep XJ. *Reason was I had a small leak that I was never able to track down with dye and so I suspected that the only place left could be the evaporator. Oddly enough when I replaced the evaporator I did not see any dye on it as well.*

After I installed the evaporator and put the dash all back together. I pumped the system for 30 minutes and the gauge read -28 on the low side. Now here is where I think I may have made some big problems. I turned the engine on and began charging with both the high side and low side valves open. I noticed this right away when I saw my low side shoot up to 100 psi. I turned everything off and pumped the system again for 40 min. to make sure all the air was out and got -28 on the low side. I put one can in and had pressures on the low side stay at 35. I closed the valves and put on the second 12 ounce can and instantly the pressure shot back up to 100 on the low side. *The high side valve was closed for both cans*

During this process the compressor has never kicked on and I am not sure why?

My two thoughts are:
- Possible bad expansion valve. Not sure what the symptoms would be if it was bad. The second thing is when I reinstalled the expansion valve I am not 100% sure if there is a front or back to this. Meaning does it need to be flipped over because the freon only goes in one direction?

- Is my compressor bad (worked before the evap. replacement)? How could I tell if it is bad?

Thank you for your help here as I am not sure what my next step is!

InitialForce

Your compressor has a clutch on it. There is a wire coming from behind the pulley on the compressor. Take a jumper cable and energize that cable on the connector side (be careful not to ground out your battery, the clutch uses the compressor itself as the ground) If the compressor starts to work then your compressor and clutch should be ok.

Its normal for your low side to reach 100+ psi btw with the compressor not running, mine does and my AC works great. If your compressor is running and you are seeing high pressures on the low side, that's when you got a problem. Reference an AC chart (pressure vs ambient temperature) for the actual pressure once you get the compressor running.

Check the clutch and if the clutch engages while being jumped you need to start looking at the electrical side of things. You have a high cut off on the high side and a low cut off on the low side of the AC system that will disconnect the compressor clutch. I am not familier with the parts under the dash, that's one area i never had to mess with.