POA valve cleaning and calibrating

[coolbreeze]

Hello everyone..
I just joined this forum today and I already have a question. But first a little info about myself.

My name is Dave and
I'm from northwest Indiana and have been a domestic refrigeration and air condtioning tech for 45 years.
I own a '55 Chevy with retrofit A/C that I installed myself as well as 2 Chevelles with factory A/C....a '68 and a '69 that we've owned for some 50 years and have given them to both of our sons. Right now I'm in the middle of restoring the '68 and at present I'm attempting to put the factory air back to original as possible with R-12 since I have plenty left. I just ordered a new evaporator coil as the original one had a couple bad leaks that I found.
I have a new condenser coil, compressor, hoses, and thermostatic expansion valve. What I would like to know is...
What is the best solution or method of cleaning the POA Valve And...can I re-calibrate it myself or at least check the calibration?? Any help would be very much appreciated. Thanks.

[Dougflas]

There were instructions on testing in the tips section but they are long gone due to upgrades. POA lo side should be 28 to 32 PSI with r12 depending upon your sea level. Test off the vehicle by connecting high side hose to shop air about 65 to 75 PSI. Connect manifold middle hose to input of POA and low side of manifold to side low port of POA. Readings of low side should be 30psi. Do not change schrader to a standard one as they are special. There is an adjustment screw on POA at input that we turn 1/4 turn counterclockwise for R134 to get 26psi low side. To test on vehicle simply unplug the fan motor ona fully charged vehicle. Low side should be 30psi.

[Tim]

Wow, just noticed all the archived posts are gone. Good thing I paid a professional to mess things up as bad I as could have done.

[coolbreeze]

Dougflas..thanks for your reply. On my POA valve I can see a hex nut inside the male threaded end. Is that the adjustment screw?
Also what can I use to flush and clean the valve? Is R-11 flush permissible or should I use something more mild?
Keep in mind that the system hasn't been in operation for like 25 years.

[Dougflas]

yes that is an adjustment screw. You would use a 7/32 socket and probably a pair of long nose piers. The socket will hold the adjustment while you tighten the screw. It is bear and you will see what I mean. If using R12, you should not have to touch it. I would use clean mineral oil for flushing. The rubber diaphram will be brittle. These POA's are normally not available any more. There is a company that will rebuild them but who that is escapes me right now. I have seen one that had an EPR valve as the main item in them.

[coolbreeze]

Thanks again..yeah there's a place in Tampa Florida that restores or rebuilds anything that's vintage factory air from the 50's through who knows.

[Tim]

As well as JW.

http://autoacsolutions.com/