#1 Is there a way to test the suction throttling valve?.  I have tested the vacuum power unit and it holds vacuum so i know the diaphragm is not leaking. Can you test the function of the valve itself without disassembling it or charging the system to see if it functions. The system will be charged with R12 . #2  Who rebuilds the original accumulator dryer with new desiccant besides classic auto air located in Tampa FL ?     I have a 1964 shop manual, it instructs you how to disassemble & repair it & adj it, but no test procedure to insure that it functions correctly. Thank you

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#1 Other than testing the vacuum power unit, I don't know of a way to test the valve itself with a fully charged system. It is a simple valve with spring pressure (including the vac power unit) on one side & pressure from the freon in the evaporator on the other side. As long as it's clean & moving freely in the cylinder, it should be good. The weak component on these tends to be the STV diaphram (different than power unit diapram). If this leaks, your freon will escape. After a few have gone bad on me and they now want $115 for them, I converted my system to a clutch cycling system. So far I have been happy with it.

#2 I don't know who rebuilds them but bought a replacement at Autozone. It is slightly shorter that the original but wasn't hard to adapt the bracket to fit it. Are you going for 100% authenticity? 

 Kurt It's going to be a driver for now , but i like to keep it original. Where did you obtain that seal? do they fail regularly?

I have had leaks from this STV diaphram a few times over the years. It looks like Old Air Products and Original Air Group have them.





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