One question I often find in my email has to do with the writer’s A/C in their car. Many times, it has recently stopped working and the question posed is about the availability of parts to get it running again. That said, most readers know that complete aftermarket kits are available, but those require the addition of a late-model Sanden 508 compressor. Therein lies the rub. There are still many enthusiasts that do not like the look of a new compressor on their classic.

However, General Motors used a variety of compressor models throughout the years and identifying which you have is paramount to know your options. The first compressor we’ll look at is the GM/Frigidaire R4. This is the short (7 1/2-inch) and fat (7-inch dia.) compressor found on later GM vehicles. It delivers slightly less than 10 cubic inches of displacement per revolution. It is small than the A6 compressor we’ll talk about next and is much lighter due to its mostly aluminum construction.

The R4 Compressor was/is a decent unit when new. We recommend avoiding reman units.

The GM/Frigidaire A6 compressor is longer and has a smaller diameter than the R4 compressor. It shares the same basic design as the late-model Sanden unit, with one additional cylinder. It is larger, both in capacity and external dimensions. Overall dimensions are roughly 12 1/2 inches long and 5 inches in diameter. It delivers slightly more than 12 cubic inches of displacement per revolution.

When I get a question about rebuilding a stock-appearing A/C system, I typically direct people to Old Air Products. Established in 1989, the company has been manufacturing A/C, heat and defrost systems that fit any vehicle.

As parts for older vehicles began to get harder to find and government regulations for automotive refrigerants made it difficult to repair factory A/C systems, Old Air Products started manufacturing many new replacement parts such as hose assemblies, evaporator cores, blower switches, vacuum actuators, and control cables.

When it comes to replacing a factory R4 compressor, you have a limited option. “We do not stock any R4 compressors and do not recommend using a remanufactured R4 compressor,” states Clint. “If the customer wants to maintain an original stock appearance with an original R4 compressor, we strongly recommend purchasing a new R4 compressor from a local supplier or replacing it with a Sanden-style compressor.” If you’re are replacing an A6 unit, you do have choices. One is a reman unit or you can upgrade to the Pro6TEN compressor.

The Pro6TEN compressor is a bolt-in replacement for the GM Frigidaire/Harrison A6 compressor. This new design is specifically engineered to fit original A6 mounting brackets and A/C hose assemblies. This compressor offers the efficiency of a Sanden compressor and retains a stock-ish appearance. If you paint it black, it would probably be unnoticeable to the casual passerby. It is a highly efficient compressor that offers smoother, quieter operation, than the stock A6 unit, and creates less vibration and engine drag. That in itself allows for increased fuel mileage and improved engine and cooling system performance. The aluminum body of the Pro6TEN is 52-percent lighter than the original A6.

“The Pro6TEN compressor offers a unique opportunity to maintain a reasonably original appearance and allow enthusiasts to update their vehicle to a newer (134A) refrigerant by using it along with one of our STV, POA, or VIR eliminator update kits,” says Clint Millican of Old Air Products. “The Pro6TEN can be used with original factory components but it is normally used with a combination of other items to update and convert their vehicles to be compatible with newer refrigerants. Depending on the vehicle, these items are usually part of our STV, POA or VIR eliminator kits, expansion valve, and barrier style a/c hose assemblies. Also, a new receiver/drier or accumulator that will be compatible with the newer refrigerant.”

What this all means, is you do have options if you want to keep your air-conditioned classic Chevy cool with stock-appearing components during those hot summer cruises. Now that we’ve shown you the stock-looking options you have to rejuvenate your classic Chevy’s A/C system, you know Old Air Products is the company that can make your cool hot rod, even cooler.