Heater fan - no high and low/med are very slow

[bull]

So high is supposed to be zero resistance but it doesn't work at all. Meanwhile, medium is the only one that really does anything because low is so slow you can barely tell it's turning. I'm guessing it's a ground problem but I can't figure out where the ground is supposed to be to check it. Does it go through the bulkhead connector, is it grounded at the box itself somewhere, or am I off base completely?

[b5blue]

First pull and check the resistor coil assy. for good continuity/readings. Then check volts through the switch, even new switches can get "flash corrosion" on the contacts.  I always "field test" a fan motor before installing, I run it at full volt/amps for about 5 min then mount.

[chargd72]

Interested in this fix.  Mine does the same thing on a 3rd gen.  No High, only Low.

[bull]

First pull and check the resistor coil assy. for good continuity/readings. Then check volts through the switch, even new switches can get "flash corrosion" on the contacts.  I always "field test" a fan motor before installing, I run it at full volt/amps for about 5 min then mount.

The resistor was tested before installation, as was the motor. I didn't check the switch though.