1971 air conditioning

[Mark C.]

I have a '71 coupe with a/c. It hasn't been hooked up for awhile, the compressor was out of the car. All other parts are intact. I've been told that the receiver/dryer should be replaced since the system was left 'open'. Although pretty handy I know nothing about a/c nor do I have the equipment to work on it.....I put the compressor and all brackets back on the car. When the car is running the clutch starts to smoke a little. I had it looked at by an a/c pro, he said I need to buy a completely new system that would hold up to the R134. New compressor, drier, and a valve, $470, from AutoAir. For a total of $730 he will install it, check and fill the system. I can save $120 and install the components myself which I will do. I was wondering if anybody had any suggestions or experience on this. Is it necessary to replace the POA (?) valve also? I see there are compressors for around 160 and driers for 50 for instance at Corvette Central. Can I just replace these parts, have the system leak tested and charged, and have a good dependable and COLD a/c system. Any help or advice would be greatly aappreciated, Mark

[Terry M.]

Re: 1971 air conditioning

Many vehicles originally equipped with R-12 have successfully been converted to R-134a without changing anything more than the gas in the system. In theory the hoses should be replaced with barrier hoses, o-rings replaced with o-rings designed for R-134a, and system lubricant replaced with PAG oil.

To do a successful conversion the system MUST be functioning properly before the new gas is introduced. So in your case one would have to find out what is causing the clutch to over heat. If the system was open to the atmosphere the receiver/dryer should be replaced, and the system should be flushed with a fluid designed for flushing AC systems. The person who looked at the system may be concerned that with the system open to atmosphere moisture may have entered. If that has happened, acid may have formed inside the system and has or will corrode the parts from the inside. He may be protecting himself from a comeback by recommending the entire system be replaced. Without examining the system, and knowing more of the history, one can not tell. I suggest, just to be sure, you seek a second opinion from another AC shop regarding what is needed to repair and convert your system.