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need help with prognosis

slopoke on Wed September 05, 2007 9:58 PM User is offlineView users profile

Year: 1999
Make: jeep
Model: grand cherokee
Engine Size: 4.0
Refrigerant Type: 134
Ambient Temp: 86
Pressure Low: 40
Pressure High: 250
Country of Origin: United States

hey there, i have been trying to trouble shoot why my wifes 99 grand cherokee limited is not blowing super cold. i will go ahead and rule out the blend doors. they are working fine. The compressor is not cycling off, its staying on. with the system on high it is blowing about 59 degress while driving out the dash vents. So today i picked up a set of nice gauges and the low side is reading right about 40. and the high side is reading 250. this is with the engine at 2000 rpm. 86 degrees outside. any ideas on where to go? before i got the gauges i thought it would be the accumulater or orifice clogged, and i would have super high pressure. but now it seems low. i am wondering if i have to much liquid in the system. if that could make it lower and not cool properly. also when replacing the blend doors i discharged the system and after a few days sealed it back and recharged it, so i was wondering if the accumulater could cause this? thanks for any input and help, scott

Chick on Wed September 05, 2007 10:24 PM User is offlineView users profile

Did you pull a deep vacuum and recharge the system amount back into the vacuum? Add any thing other than virgin R134a and oil? Charge the system amnount as listed on the underhood sticker/ Is the suction hose going to the compressor from the evaporator as cold as the inlet hose to the evaporator??

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slopoke on Wed September 05, 2007 11:32 PM User is offlineView users profile

yes pulled a good vacuum and reloaded with fresh 134. yes both tubes are equally cold, getting good condesation on them. thank you

TRB on Wed September 05, 2007 11:42 PM User is offlineView users profile

Your low side is high for that ambient and RPM. How much refrigerant was added after you pulled a vacuum?


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patarusky on Thu September 06, 2007 4:26 PM User is offline

Tim- You said the low side is high for the temp he posted. Would more refrigerant bring down the low side (which should equal cooler vent temps) ? I'm having a problem with a dual system that seems to have the same problem he has. If I run just the front the numbers are great -low-32 high-180 and the vent temp is 42. But when I turn on the rear the numbers change to - low-56- high-175- vent temp- 64 front -72-rear. Plus when I run just the rear alone I get- low-35-high-185- vent temp-60. Outside air is 82 degrees and 50% humidity.I don't have a stock fill amount since this is an aftermarket set-up so I'm slowing adding 134 till everything is working and chilling and then adding 2 OZ at a time and monitor pressure and vent temps but I don't know when to stop adding charge. I don't want to overcharge but everything appears to work normally. Could it be that using both front & rear is raising the pressures and hence the vent temps? Would the accumulator restrict the increased flow of both systems or possibly an in line filter not handle the flow demand of 2 systems? Thanks

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