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Pressures

ghiotom on Sat August 11, 2007 7:09 PM User is offline

Year: 1996
Make: Jeep
Model: Grand Cherokee
Engine Size: 5.2
Refrigerant Type: R-134A
Ambient Temp: 92
Pressure Low: 65
Pressure High: 340
Country of Origin: United States

The problem: insufficient cooling at idle.
The evaporator was leaking, so it was replaced with a brand new aftermarket evaporator and accumulator.
The system was purged, evacuated, and filled with 28 oz. (best I could measure) R-134A and 3 oz of PAG 46 DEC oil.
The inlet and outlet to the evaporator is cold and sweating.
Numbers: Ambient 92 F RH 63%
Idle - Lo Side: 70 Hi Side: 345
1500 RPM - Lo Side: 63-65 Hi Side: 330-340
When I spray the condenser - Lo side: 43 Hi Side: 200 Vent Temps drop 6-7 degrees, the pressure drop occurs in about 20-25 seconds
and then after 3-4 minutes is back to where it was.
Lowest vent temps at idle when ambient is over 90 are around 50 degrees, but it will cool down to around 41-42 degrees after driving
for some distance. I also installed a brand new fan clutch. Engine temps appear to be normal.
Any ideas where to go from here? Thanks.

JACK ADAMS on Sat August 11, 2007 7:42 PM User is offline

You say that the system was purged, do you mean evacuated? Pulling a Vacuum for at least an hour would be acceptable @ 28-29inches of vacuum. You have the correct amount of refrigerant in the system but it sounds like you have Air in the system as well. Try to reclaim the refrigerant and pull a vacuum for the hour and recharge with 28oz of pure virgin refrigerant 134a. Repost with results.

ghiotom on Sat August 11, 2007 7:58 PM User is offline

Yes, the system was evacuated. I pulled a vacuum for 1.5 hours, held a good vacuum for an hour and then repeated. I then charged into the vacuum.

TRB on Sat August 11, 2007 8:21 PM User is offlineView users profile

28 ounces is the correct refrigerant capacity for this vehicle. Areas of concern to me would be too much oil and or poor air flow across the condenser. Pressures are very high in my opinion.

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ghiotom on Tue August 14, 2007 10:09 AM User is offline

I'm thinking air flow issue, since it works fine while moving. The fan clutch is not OEM (it's from Advance Auto Parts), but it does roar when I rev it up. The fan sits almost completely within the shroud.
I think I will replace it with an OEM clutch, but I have a feeling that I'll spend $200 and it will make no difference. The condenser has no obstructions (dirt, hair, bugs), but I'll give it a good cleaning and see what happens. Thanks for the help guys.

Wet in Washington on Tue August 14, 2007 8:00 PM User is offline

Go with the OEM fan clutch. I tried an aftermarket from Hayden and it was a P.O.S. It wouldn't lock up no matter what the temperature was. The OEM's are twice the price, but you get what you pay for. And make sure your condenser it clean, that makes a difference too.

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Never take life seriously. Nobody gets out alive anyway.

Edited: Tue August 14, 2007 at 8:01 PM by Wet in Washington

ghiotom on Thu August 16, 2007 9:36 AM User is offline

Well, I just found out the OEM fan clutch from Jeep is $295!!!

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