Heater fan

[Matty]

I decided to get another job out of the way today, and that was to get the heater fan working. I've pulled the fan out of the housing cleaned the terminals on the fan and connected it to a 1A 12v power supply. All works well, now this is where it's gets confusing!

I've measured the voltage at the terminals in the car, and they read 11.6v no matter what position the switch is in (battery reads 13v across terminals). When i fitted the fan it didn't work. So I then decided to clean the terminals in the car with Emory paper and give them a squeeze to close them up, refitted fan...nothing. I then ran some wires from the terminals in the car to the fan and switched the switch on...nothing!! I left it switch on and there was 11.6v at the motor. So this has left me in some confusion, as to what is wrong? And Should I be seeing 13v at the motor?

[Jonny5]

You'll be needing a new fan resistor.

https://www.rtoc.org/boards/search.php?searchid=14135

[Matty]

So by the looks of things that resistor is basically an over temp fuse? Wouldn't that make the circuit go open circuit and see no voltage at all at the fan? Or does it limit the power supply some how?