Quote: Originally Posted by
NitroLarry 
Your new Dual PWM FET driver looks real cool! Its listed to have a 20A continuous rating. It's been a long time since I clamped a blower motor, but almost all are protected by a 40A fuse. What maximum rating do you see this add-on handling?
I happen to live in Canada and often see blower motor resistor failures where the amp draw blows the thermal fuse on speeds of 1-3 of a 4 speed dial. So no where near full draw cause only position 4 is full 12 volts.
The thought of having a 15 or more blower motor settings is really exciting. The perfect speed can be achieved.
Thanx.
You will find that if there is a 40A fuse the operating current of the blower would be ~half that. A bit of slack is left due to the initial inrush current of the blower starting up.
From the 4 vehicles I tested it on, the maximum Blower current I found was 18A. If you have the FB current meter you could use that to test what yours draws, else you you need a high current meter.
The Fet Driver can easily handle a 40A surge which would be enough to blow the fuse. As it stands the Fet Driver can actually handle 25A continuous.
About the resistors there inefficient and get really hot! With this unit you just have to connect it to the highest position of your blower setting which would be 12v.i.e bypassing the resistors
Linear Mode
