vintage auto air conditioning systems in most mid 1960’s to mid 1970’s GM vehicles and some 1970’s Fords include a POA valve. POA – an abbreviation for Pilot Operated Absolute – valves are suction valves used to prevent the AC system’s evaporator from getting so cold that it freezes. In some air conditioning systems, this function is handled by a thermostat. In most mid 60’s to mid 70’s GM vehicle air conditioning systems and on some 70’s Ford systems a POA valve was used. Frigidaire and Delco were the primary manufacturers of these valves.
We spend a good bit of time dealing with these valves, and regularly get questions from mechanics and car owners. Because of this, we developed a fairly comprehensive FAQ section related to POA valves on our web site – sort of the Wiki of POA . We figured a reminder of those questions and answers might be helpful. Below is a summary index of the Q and A:
- What does a POA Valve do?
- How does a POA Valve fit into the air conditioning system?
- Are there different types of POA Valves?
- Any POA Valve issues when restoring car?
- Is my POA Valve failing?
- Suggestions for a failing POA Valve?
- Any POA Valve issues when converting to 134a?
- What is POA Valve Reconditioning?
- What is POA Valve Rebuilding?
- What’s a Core Charge?
Suspect that your POA Valve may be failing…
Depending on the model used in your vehicle, Classic Auto Air may be able to rebuild your POA valve. If your vintage auto air conditioning system’s POA model can’t be rebuilt, we may be able to recondition yours or offer an NOS replacement.
If the POA Valve is failing, you’ll have little or no cold air coming out the vents when the air condition system is operating and the high side reading will be normal but the low side reading will be high (Because the failing POA Valve is letting high pressure vapor into the low side of the system).
To find out if the valve is functioning correctly, most customers choose to send us their POA Valve and let us test it. If it passes a series of tests, we can recondition and recalibrate it for you. If it is a Frigidaire Valve and it fails any of the tests, we can completely rebuild it.
Alternatively, you or your mechanic may be able to determine if your POA Valve is failing during system evaluation using gauge manifolds. A POA Valve will generally fail in the open position, letting high pressure vapor into what should be the low pressure side of the A/C system.
Check out the Recondition and Rebuild questions in our complete guide to POA Valves.
A couple additional links that may be helpful: