I have a 72 Skylark that I just bought and the compressor is locked up and needs replacing. It currently has a non-Superheater unit but there is a 3 wire connector with no place to connect. Does this mean that it originally had a Superheater switch unit and a regular comrpessor was added later? If so what exactly is the difference and should I go back with a Superheater compressor now? Thanks
You should be able to just put another compressor on it and have it work correctly. Make sure to put a new drier/filter in place and if you can get the poa or orifice tube out to check it for debris. Jim
A superheat compressor is just a regular A6 that has a place in the rear head for a superheat switch. If the refrigerant gets too low in the system (or a few other issues) the switch closes and blows the thermal limiter fuse. The Thermal limiter plugs in to the 3 wire connector that you mentioned. You can use any A6 and it will work fine, but without the switch you will lose the protection of the thermal limiter. You would just jumper across 2 of the wires on the connector (each end IIRC). Most reman or new A6 compressors today have the port for the superheat switch. It's capped off if not used. Reman: https://www.ackits.com/pc/000016CP/Buick72Skylark5-7/000016CP+-+Remanufactured+Compressor++-+Clutch New: https://www.ackits.com/pc/20-10649/Buick72Skylark5-7/20-10649+-+New+Compressor++-+Clutch Since the system is ~40 years old, there's more work to do to make it functional and reliable than just replacing the compressor. Some time and a few $ spent now can save a lot of $$ and disappointment later. The compressor could be frozen due to moisture and internal corrosion. If so, every part needs to be inspected and replaced if corroded internally. Any good parts need to be flushed if reused. Pressure testing the heat exchangers is also a good idea if corrosion is a concern. If the compressor is locked up due to an internal failure, the entire system needs to be flushed to remove debris from the compressor. All of the ~40 year old orings and sealing washers should be replaced and the POA valve tested (and adjusted for R134a if applicable). The Expansion Valve should be tested or replaced also. It would really suck to find out any of the above mentioned parts are bad after replacing the comp and charging the system. As swampedge mentioned, the receiver/dryer MUST be replaced regardless of any other checks or repairs that you do. I think he meant to say the Expansion Valve inlet screen should be checked for debris though, not the POA. He's absolutely correct. Checking that screen can tell you a lot about what's inside the system that shouldn't be there. All of this sounds like a lot of work, but it really isn't. It's mostly a bunch of small details. Aside from having the POA valve tested/adjusted, you can do it all on a Saturday and be cruising in comfort on Sunday. You'll need access to a good supply of compressed air, a vacuum pump and a manifold gauge set as well as common hand tools. Good Luck
