[LKLusza]

Hi All,
My 1970 GTO w/factory A/C uses the A6 type compressor and POA valve. The compressor failed (noisily) and I'm concerned about debris and contaminants that may now be spread throughout the system.
It will be returned to service using a reman A6 compressor with a new expansion valve and drier. It'll be converted to R134. Circumstances force me to continue with the original condenser out front, so it is what it is. I have a set of gauges and know how to adjust the POA for R134 prior to reassembly, and that the A6 compressor uses 11oz of the appropriate oil. I'm also aware that all of the o-rings will have to be changed throughout and the tools and concept of system flushing are easy enough to grasp. However, my question is this:

What advice can anyone give about flushing or cleaning the original POA valve? I'm concerned about the flush reacting with the various seals and such contained inside as well as the ability to adequately dry it out and relubricate the internals. It's silly to flush the system and not do anything about the POA valve. I can't find anyone talking about this anywhere on the Internet. Thanks!

[gto4ben]

The stock expansion valve has a metal screen that would have stopped most of the debris from circulating through your system. You're replacing it but perform an inspection to see if there is any metallic debris which would warrant a really thorough flush.

Since AC flush is expensive, I use lacquer thinner as an initial flush and then use the AC flush in a final cleaning. The POA can be flushed while connected to the evaporator or stand alone. I recommend that the POA be bench tested before installation and cleaning since the refrigerant and oil may have been burnt & contaminated causing the POA to stick. You can plot the input pressure vs output pressure and note the point the POA regulates the pressure. A bad one will show not regulation and the output will follow the input pressure.

[LKLusza]

Hi gto4ben,

Thank you for the swift reply and pictures. I'll be sure to check the screen. The POA testing your recommending - would the valve adjustment procedure for use with R134 accomplish the same thing? I can do that while it's attached to the evaporator. Or, should I make the adapter as you did and do it on the bench? Thanks.

[gto4ben]

You can test the POA while it's on the car by applying air pressure directly to the TXV inlet. At ambient temperature, a working TXV will be open and not restrict the flow. The photo shows a blowgun against the TXV.. I made a fixture to connect the air pressure to keep my hands free to record readings.

POA adjustment is on the evaporator side so having an adapter and bench testing makes it easier to teardown and reassemble.

[LKLusza]

Excellent! Thanks again for the pictures and information.