I have my A/c blowing cold as ice but it is not cycling off (89 ram 50)... Trying to avoid taking it to a shop but any suggestions on where the high pressure switch is and how to test it? The expansion valve is against the firewall and it has a copper rod (looks like some sort of a thermostat) that slides in the cold hose. Hopefully this makes sence to someone and will be an easy fix. Thanks!