It's the voltage that is determining the speed of the motor guys. That’s what the switches are doing, adding voltage dropping resistance to the circuit.
Without actually measuring the flow, how much air is being moved is highly subjective and simply subject to what an individual is used to. So if you’re expecting the AD fan to move as much air as your 2007 Chevy truck forget it. My truck, a 1950 stock 6v fresh air heater has a rebuilt switch, a too hot to the touch coil, new water and air hoses and it delivers just enough air at the defrosters outlets to keep the frost off the window. There isn’t a lot of air moving around there. I’ve not had any problems driving down to temps below freezing.
Denny Graham
Sandwich, IL
