[HWYSTR455]

Yes, it's with the POA valve that remains 'on'. The 'update' valve is the one that cycles. It in my understanding has nothing to do with the compressor.

"A thermostat prevents the Evaporator from freezing by cycling the Compressor on and off based on Evaporator temperature. A POA Valve prevents the Evaporator from freezing by by-passing excessive system pressure. Note that in a POA Valve type system, the Compressor runs constantly whenever the air conditioning system is operating."

Source: https://www.originalair.com/about-po...is%20operating.

"POA valve update kits convert the A/C system to a cycling clutch type system as found on later model vehicles."

This is from an OAP Amazon listing for an update valve, which is not a POA:

https://www.amazon.com/Valve-Update-...TD-&hvexpln=73

They make 2 different update valves, one for R12, and one for 134.

Sanden does make compressors for both R12 and 134. In some cases, it's just a matter of changing to the compatible oil.

This is Sanden's 'official' stance on R12/134a:

https://www.sanden.com/objects/retro.pdf

.