Originally Posted by haroldo

As to HVAC's fan controls, when you adjust the temperature higher or lower, more often than not, the only thing that changes is the fan speed. Once heat is on, your only choice is more heat or less heat (assuming, of course that heat is properly directed to the floor for maximum efficiency...heat rises). So if your set to 68 and your cold, changing the temp setting to 70 will cause the system to spin the fan faster. Heat is produced by the engine and forced through the ducts by the fan. You want it hotter, the fan goes faster.
I'd rather adjust the temp up a degree or two, or even resort to moving my hand the fifteen inches to the manual controls, rather than monkey around with the wiring on the car. But hey, it's your car.