Testing the Heater Blower Resistor

[shtu]

Since I have it in bits anyway fixing it, might as well write down some useful info.

Resistance testing this is quite simple once you figure it out.

Step 1 - Thermal fuse.
It's the little cylinder at the top. It should be less than 1 ohm. It it's open circuit, stop now and buy a replacement part.

Step 2 - The individual resistors.

If the thermal fuse is fine, you can test each winding.

I didn't use the plug terminals, and used the obvious "bars" of the resistor itself.

I placed this on a surface with the screw hole on the left, place one probe on the leftmost bar, then the resistance from there to each of the other bars is

1.0
1.8
3.5 Ohms

If you get zero Ohms testing like this, move the probe from the leftmost bar to the right hand side of the fuse, and check again. If you now get resistance, it's the thermal fuse.

[xavier988]

That’s a really helpful way to break it down. Testing the thermal fuse first is smart, saves a lot of time if it's gone

[shtu]

Measuing the new one, the thermal fuse is about 1 ohm.

Another top tip - the cheap aftermarket resistor I bought wouldn't slide into place. A close look, and there was a small extra tab of plastic that was preventing it. 30 seconds with a hacksaw and file, fixed.