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Dual air - cold rear, hot front

padgett on Sun July 25, 2010 3:45 PM User is offline

Year: 1992
Make: Pontiac
Model: TranSport
Engine Size: 3800
Refrigerant Type: r134a
Ambient Temp: 95
Pressure Low: 45
Country of Origin: United States

TranSport minivan has dual air converted to 134A some years ago. Single HR6 compressor. Pressures seem fine but front a/c is blowing near ambient (100f in 93f out) while rear is properly cold. Hot/Cold switch on dash makes front vents go from room temperature to HOT so diverter is working. I am suspecting a clogged oriface tube (rear is POV). Change from operating fine to nada was sudden. Other suggestions before I open the system are welcome.

Many Carpets

GM Tech on Sun July 25, 2010 4:24 PM User is offline

Typical low charge scenario, find and fix leak- most like compressor shaft seal, evac and recharge to factory spec and all will be fine..

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

padgett on Mon July 26, 2010 10:04 AM User is offline

And the answer is: a failed electric fan. Once the puller motor was replaced (and those suckers are expensive) it is cooling properly again.

The remaining question is not why was the dash air warm but why was the rear air still cool. AFAIK they both use the same compressor/condenser.

Many Carpets

CCWKen on Tue July 27, 2010 12:51 AM User is offlineView users profile

If the fan failed, how was it "blowing near ambient"? Air must pass through the evaporator to produce cold air. Otherwise, it's just another piece of pipe in the system.

Ops. Never mind. You were talking about the condenser fan.

Ken Kopsky

Custom Car Works
"Rules are for the guidance of wise men and the obedience of fools."

Edited: Tue July 27, 2010 at 12:53 AM by CCWKen

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