jurgovan

I have a 99 grand cherokee limited with V8 engine. I have replaced almost all components of AC system in the last year. Started with evaporator and liquid line with orifice tube, then condenser, then compressor (all at different times). After it was evacuated and charged the latest time, it had good cold air and then now not as much. The driver side vents are colder than the passenger side. I cut the air handling box open since I suspected blend door issue but the blend doors are working fine.

I also noticed ice under the air handling box under where the evaporator is located. I suspect there is sufficient cold air coming from the evaporator but it's not really cold from the vents.

Could there be excessive heat coming through the blend doors warming the conditioned air coming from the evaporator? The passenger side blend door is against the firewall and feels warm. Also, the heater core was too hot to touch. I assume it's normally that hot?

I have not hooked up a gauge to the low pressure side to monitor the pressure.

Another odd thing is there is a loud clicking noise coming from the compressor when the AC is running. It also doesn't seem to be cycling but I was running it on max so this is expected. This is my second replacement compressor and I purchased them at Jeepair.com. Any experience with their compressors that anyone would like to share?

Final odd thing is that it seemed to be cooler at lower engine RPMs (especially idling) and warmer while driving about about 45 mph or so.

I don't want to keep dumping money into this AC system but feel I'm so close to a good system since I replaced all major components.

thank you,

tony

bones99xj

Did you check all your vacuum lines?? Vacumm tank?? Fan clutch and comp clutch relys???

jurgovan

I did not replace the compressor clutch relay and I don't know about the vacuum lines. What would indicate a bad vac line?

I checked the pressure on the low pressure line at idle and 1800 rpms and at idle it was about 50 psi and at 1800 rpms, it cycles between about 72 and 30 psi. The compressor clutch seemed to engage without issue. Do these pressures seem correct? I did not replace the switch on the accumulator yet.

Any other thoughts with this new info?

jurgovan

After some more research online, a possible issue with the high low side pressure at idle was overcharged refrigerant or condenser fan issues. So, sure enough, my condenser fan isn't running. I sprayed water on the condenser to help cool it and the pressure dropped to about 25 psi, which seemed to be more in line with what would be expected. So, I will hook up the fan directly to the battery to see if it's the relay or not. Who knows, maybe I pinched a wire when taking the radiator out 3 times last month.

Still though, I am not getting much cold air out of the passenger side vents. I cut the hvac case open and verified the blend door is seating. Once I get the condenser fan working, maybe the system is undercharged and I'm not getting good cold distribution through the evaporator and it's just warm on the one side.

The troubleshooting will continue.

Let me know if you have any other thoughts.

jurgovan

I changed the radiator fan relay, so that works now. I hooked up gauges to the low and high side lines on the AC and at idle, had about 35 psi and 250 psi, respectively. But then at about 1500 rpm, the condenser started short cycling. The pressure was climbing a bit on the high side but I can't recall how high it got. We did let some of the refrigerant out though as it climbed, which brought the low side down a bit.

I was thinking there could be some build up in the lines, maybe excessive oil or some other contaminate clogging up the orifice. Anyone agree with this assessment?

I just replaced the accumulator and liquid line with orifice last year. Should I replace them again but blow the lines out first?

Any other thoughts?

jurgovan

Can someone send me the applicable AC pages from the FSM, including charts if available? Again, this is 99 WJ with 4.7L engine.
Thanks

Lyon

Cold vents on one side and ice forming on the evap coil indicate low refirgerant charge.
Proper vacuum must be put on the system before charing freon and oil levels are very important.
If you are getting high discharge pressures you either have air in the system or you have air flow (cooling) problems across your condensor coil. Try cleaning the coil with a low pressure hose from the inside (under hood) outwards towards the nose of the Jeep. Basically, it's the opposite way the air flow normally goes. You MUST have clean coils for air to be pulled across for proper cooling. The same goes for the radiator. As the cooling gets better on your condensor, your discharge pressures will drop as well. Goodluck.