Well, some progress made today. I cut the two wires that feed power to the servo motor installed a DPDT switch. In 1 position the switch allows "as it was" operation of the servo; in the other position the polarity is reversed and the servo drives to full heat! The only problem now is since the blower operation is dependent on the servo position none of the blower on functions will work except DEF. Oh well, at least I have heat now until I can get the full cool servo control mess figured out.