AC Heater Switch help needed with swap

I'd say something is mis-wired or something wrong with the switch. These don't have the "trick" defrost AC like modern vehicles (where the compressor runs when temps are cold, to help dehumidify and defrost.). These old girls should only activate the compressor on call for AC

To tell you the truth, I've not played much with factory AC switches. My old RR had aftermarket "knee knocker" air, and most anything lately (except the 74 Scamp) does not have AC. The Scamp? Well, it's still tarped from winter LOL