The system pressure should not be high enough when the compressor is not running to trigger the high pressure switch. It should normalize down to a fairly low level. It is only when the compressor is running that the high pressure switch should activate if the pressure is too high.

If the system pressures are proper, then the high pressure switch may be going bad. If the switch is bad, then the system will need to be evacuated prior to attempting to replace the switch.

 

Thats what I thought you were going to say