Compressor stay ingauged new system, pressure balance is correct. i know the system is either on or off. how do the temperature controls work?
There is no temp sensor on a 69 Skylark. The POA valve controls the evaporator temperature right around 32 degrees without icing up, at all loads and RPMs. The dash located temperature control operates a blend door which adds more or less heat into the airstream from the heater core depending on its position thus allowing you to adjust the outlet air temperature to your liking.
in that case if you have the CCOT system, there is a pressure switch that cycles the compressor on and off at a temperature/pressure that allows it to stay as cold as possible without icing up. If the compressor runs continuously, the low side pressure, is not getting below the setpoint of the pressure switch. This can be due to problems with the system or simply a high load. You can test the switch by installing a gauge on the low side and disconnecting the blower motor while the compressor is running and the engine is around 1500 RPM. The switch should open and disconnect power to the compressor somewhere around 25 PSI. Is your A/C working properly, blowing cold air?