Automotive Air Conditioning Information Forum (Archives)

bob234 on Tue August 17, 2010 10:55 PM

Year: 1992
Make: Chevrolet
Model: Silverado
Engine Size: 5.7
Refrigerant Type: R134A
Ambient Temp: 95
Pressure Low: 55
Pressure High: 320
Country of Origin: United States

I have a 1992 Silverado that completely lacks cooling at idle. Driving around, or spraying the condenser with hose in the driveway, it will reach 40 degrees. Idling it will creep up to 65-70 degrees depending on how long I sit. What option should I pick. I got it narrowed down to 3 and I do have 10 cans of R12 in the garage.
#1 - Have the R134A evacuated at a shop, change the orifice tube from the ford blue back to the factory GM white and put R12 back in, keeping the original condenser.
#2 - Change the condenser to a parallel flow, keep the ford blue orifice, and keep it R134A.
#3 - Keep the original condenser, and the blue ford orifice, but add dual pusher fans in front of the condenser.

This system is not overcharged, and when the engine is cool, the low side is 35 and blows great idling. Just when the engine warms up it will go to 55psi low side. This symptom definably narrows it down to a inefficient condenser.

TRB on Tue August 17, 2010 11:00 PM

Size to size a true multi veined parallel flow condenser is about 1/3 more efficient than a T & F condenser.

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emsvitil on Wed August 18, 2010 12:59 AM

What about getting more airflow across the condensor at idle?

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Ed
SoCal

NickD on Wed August 18, 2010 9:28 AM

Can't expect any cooling with pressures like 55/320 psi. 55 with superheat would barely give you 70*F vent temperatures, even more with hot air coming in through the vents. And this assumes you are providing the orifice with a solid liquid and not foam.

Air conditioning or conditioner air means the same thing, key word is air, must have good airflow, something you normally don't find in either an older or a newer vehicle, always the first step. I tend to look at the condenser as being a stone stopper and an insect accumulator, the blower wheel as a debris chopper and the evaporator as a filter to collect all that debris.

Either R-12 or R-134a cools very well, up to you and the condition of your existing system to either upgrade it to a good R-12 system or a good R-134a system. Your OE condenser is already 18 years old, if it need replacement, would recommend going to R-134a, more than likely have to change the cycling switch and accumulator as well, so can go with R-134a.