Older cars with factory air come equipped with a POA valve, which is a mechanism that prevents the Evaporator from freezing by by-passing excessive system pressure. In last month’s Tech Talk Blog, we explained how to determine if your POA valve is failing and whether or not the POA valve on your ac system can be rebuilt. Sometimes we get questions about adjusting the POA valve, so we thought we would share this information too. Adjusting a POA valve is quick and easy if you simply follow these steps…..
The POA Valve regulates the pressure inside the Evaporator. It is set for R12′s optimum pressure of 29.5 PSI. To get maximum efficiency from R134A it has to be adjusted for a lower pressure. Looking into the inlet of the valve (through the fitting where the hose to the Evaporator goes), an adjustment screw with a locknut can be seen. Loosen the locknut and turn the adjustment 3/4 turn counter-clockwise. This adjustment lowered my vent temperatures from 52F to 43F on a 90F day!br> br>