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85 Suburban

ChevyMan on Sun August 26, 2007 7:35 PM User is offline

Year: 85
Make: GMC
Model: Suburban
Engine Size: 350
Refrigerant Type: R134
Ambient Temp: 85
Pressure Low: 28
Pressure High: 235
Country of Origin: United States

I was wondering how I did. This was retroed a long time ago by myself. It has a leak that I need to find, but in the meantime I just charged it up. I used 48 oz of R134a. I think this is actually 100% of the R12 capacity. Readings were taken at fast idle, 1500 RPM or so by ear (no tach). Low 28 PSI, High 235 PSI, Vent 40. Inlet and outlet of evap feel the same. Fan clutch engaged and pulling lots of air. Accumulator dripping lots of water.

Anyway, my question is this. How good is this. This truck is a lot to cool with just dash air, as there is no rear unit. The other day I glued 1/2" styrofoam insulation to the underside of the roof to cut down on the heat load. All the windows are tinted also. Is this the best I can do to keep cool?

TRB on Sun August 26, 2007 7:52 PM User is offlineView users profile

That is very good considering the area you are cooling with a single system. Nothing wrong 40 degrees in a little Honda!


When considering your next auto A/C purchase, please consider the site that supports you:

ChevyMan on Wed June 10, 2009 8:59 PM User is offline

ChevyMan on Wed June 10, 2009 9:14 PM User is offline

Hello. It's been almost 2 years. I am having trouble with this truck. The refrigerant leaked out over the winter between 07 and 08. I did not mess with it at all last year. Now I am trying to get it to work again. I can not duplicate my success of two years ago.

I found the leak. It was the compressor shaft seal. I have replaced that. I also decided to flush the system as I never had done it before on this vehicle. I used brake clean and compressed air. I removed all the components from the truck and cleaned them out completely. I straightened some bent fins on the condenser and cleaned the evaporator fins while I has at it. I noted that there was no oil in the compressor. I added 4 oz of ester oil to the compressor and 4 oz to the drier. I installed a new ford blue orifice tube and a new drier. I replaced all the o rings. Finally I vacuumed the system for an hour and it held vacuum. I recharged it with 48 oz of R134a as before. Only problem now it that it wont cool properly.

Ambient temp: 85 degrees. Time of day: 7 PM (little sun load). Fan on high and AC on max. At idle I have: Hi - 245, Low - 42, Vent - 62. At 1500 RPM I have: HI - 275, Low - 38, Vent - 55. If I put the garden hose on the condenser I get at idle: Hi- 155, Low - 30, Vent - 50. At 1500 rpm: Hi - 180, Low - 28, Vent - 48.

The fan clutch is still good or so it seems. It is moving lots of air. It is only 2 years old. I mounted an electric fan in front of the condenser, but it does little to help the pressures. I even clamped off the heater hose. No difference. I cant figure out why it worked better than this two years ago when it had a mix of mineral oil, POE, and who knows what else in it. Do I just need to get a bigger condenser?

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