Do you have factory service manual ??? My 70 Sport Satellite is factory a/c and found the fsm, best source for trouble shooting. Perhaps you may have something wired incorrectly because in heat position, the a/c compressor should not be coming on. In def position it does, but not in heat. Also make sure the control is for 70 model year, the part number has been superseded several times over the year, and functionality changed . . . at least that is what I have found . . . good luck