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I have a 1993 GMC 1500 with a 4.3 and my AC compressor needs to be replaced. A local mechanic told me to go ahead and convert the system to R134A with a new compressor and dryer. Being mechanically inclined and doing most or all of the repairs on my own, I have never worked on AC systems before but I feel that I could possibly handle it, money is tight so my question is, would it be wise to let the shop do this work or is this something that I could handle with obtaining the proper parts in a day’s work and save about $300.00? If I do this myself by replacing the compressor and dryer, do I need to flush the a/c system? Are there any orifices to replace or add to this repair?

Let us start with the idea of converting your system to R134-A! The A/C system you have is designed for R-12 ONLY. When you convert you’re A/C system to 134-A, you are increasing the A/C systems pressures. This makes the truck’s A/C compressor work harder at higher pressures. In short you are re-engineering the A/C system that was designed for R-12 refrigerant. R-12 is still locally available for your truck’s A/C system! It is more expensive compared to R-134A. Yet, in the long run it is a lot cheaper to use R-12 than replacing A/C compressors every couple of years. Plus R-12 cools your truck’s interior a lot better than R-134A! Now to what caused the compressor failure needs to be solved before you change any parts! I suspect that you MAY have a radiator problem or something that caused excessive high side pressure to ruin the compressor. The condenser may be restricted if so, the condenser needs to flushed or replaced. The “minimum” work to the condenser is to be “flushed” to remove contaminants from the system. (Old pieces of the compressor, old refrigeration oil, acids and sludge are what need to be flushed out). There is an orifice tube that needs to be replaced as well (at least examined and cleaned). My advice is to pay an automotive professional to repair you’re A/C system correctly with a written warranty. Working on today’s A/C systems is a science. Technicians have to go to school constantly to stay up to date with the changing technology and repair procedures. Having a professional repair your truck correctly will give you maximum comfort with minimum headache and heartache!


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