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Tha AC in my 66 rdstr has not worked since I purchased it.I was told by the previous owner it needed a POA valve but learned that there was another way to fix this (I dont have the car judged)valve with some type of upgrade.Can anyone help me out with this?.
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Re: 66 AC POA valve
The factory A/C system used a suction throttling valve (STV) to regulate pressure to the evaporator. It kept the evap unit from freezing over under just certain atmospheric conditions (temp/humidity). In later era Four Seasons A/C systems, the STV was replaced with a POA valve.
There are typically two modes of failure for the STV: (1) it leaks resulting in loss of refrigerant, and (2) the valve either sticks open or sticks closed. There's a rebuild kit available to address leaking STV's and some refrigeration specialists will actually rebuild faulty STV's by tearing into them and cleaning clogged screens and/or cleaning sticky valves.
Why not attempt to have your original STV repaired first? Check the archives and you'll find reference(s) to a specialist in Florida that does such work...if you're certain of the system diagnosis.
There are also conversion kits to transform a STV based system to a CCOT system (compressor cycles ON/OFF as needed) like what was used on late era Shark cars. So, there are several ways to skin the cat depending on exactly what's wrong with your system. I think I'd start by finding a competent local A/C mechanic to evaluate your car before you run off buying/replacing this/that part though... -
Re: 66 AC POA valve
If you can, post some pictures of your system. The POA/STV are easily identified if you've seen them before. 67 is the only mid year Vette to use a POA. You most likely have an STV. Don't just throw dollars at the A/C system. As was offered, have a qualified Tech. inspect your system. Al W.Comment
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Re: 66 AC POA valve
Sometimes it may not be what they believe is wrong with air conditioning systems. I actually had the my air conditioning system checked out in 1988 by the local Chevy dealership technitions. I was out of town and told my wife to take our 1970 Corvette to dealership because the air stopped working. I am so glad they were not successful in doing what they told my wife was wrong with the air conditioning system. They said it needed a new evaporator. I was lucky in that they could not remove the big nut to the evaporator and stopped work. I got home and started reading my service manual. I discovered with the first thing I inspected that the dryer desiccant bag had ruptured and the desiccant had worked it way through the condensor to the expansion valve. The expansion valve has a metal screen that filters the R12 and was completely packed with desiccant. I replaced the screen, flushed the lines, installed a new dryer. Had the system vacuumed down and recharged with R12 and the air conditioning system was functional again and still is today. My service manual had a very good picture of the expansion valve and the screen which really helped me in selecting the right thing to check first along with narrative information to trouble check the system.Comment
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