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Dual Air 93 Suburban - Help

charliechan on Mon February 18, 2008 9:17 PM User is offline

Year: 93
Make: GMC
Model: Suburban K1500
Engine Size: 5.7L
Refrigerant Type: R-12 to R-134
Country of Origin: United States

Bear with me here. I have several questions. Truck was original R-12 until 2001. Had a leak, repaired, switched to R-134. Worked for about 1.5 years, cooled somewhat okay, then original compressor started knocking. Had system flushed, accumulator, orifice tube, compressor replaced, still R-134. New compressor/system cooled okay at highway speeds, and barely cooled at hot idle. The 2nd compressor has now started leaking and is dieing (worked from 2002 til 2007). By the way the replacement compresssor was a new R4 AC/Delco.

To put this system back in service I was wondering about the following:
1. Do I need to replace the original condenser? If so, what type, PF or the original tube/fin style? Do I need to upsize the condensor, or add electric puller fans to help with the AC hot idle output?
2. I am assuming the entire system needs to be flushed and checked for leaks again. Is there any type of mods or preventive things that need to be done to the rear evaporator assembly/TXV valve for R-134 operation. This was not modified in any way when switched to R-134 from R-12.
3. I also assume a new accumulator/orifice tube assembly needs to be installed when the new compressor is put in.

I am looking to at least place the new components into the truck to save some money on the labor. I want the AC guys to flush, vaccum check and charge the system, and not sweating the "mechanicals" of the system.

As far as low side/ high side readings, I don't have the typical numbers. I am not really an AC kind of guy, but am looking for some basic tips to help improve the system and get things "ready" for my friendly AC technicians.

bohica2xo on Tue February 19, 2008 4:10 AM User is offline

The best modification you could make would be to restore it to R12 operation...

There is a LOT of flushing needed in your system now. 2 failed compressors on a rear A/C vehicle means plenty of debris, and plenty of plumbing to trap them.

If your fan clutch has more than 50k miles on it, replace it with a new Delco part. You may be able to upgrade to the nylon fan as well - I don't have the book in front of me right now. The fan clutch is the first place to look when you have poor idle performance.

Upgrading the condensor helps, but installing a PF unit will require custom hose fabrication.

The rear TXV will need to be removed to flush the system properly. Replacing it is an option, check it for debris & internal corrosion. The lines to the rear of the vehicle need to be flushed well, and blown clear with at least 25 cfm @ 100 psi for several minutes. Without enough airflow, you will not build the same velocity as a running system. You need to be sure all of the flushing agent is removed, or more compressor failures will result.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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