help, similar problem to the only working on setting 4 ones but my heater works on all four settings then after about a minute it gradually fades to nothing. If i forget to turn the switch back to 0 then i get a strange noise (humming like) from under the dashboard which goes when i return switch to 0.... I can turn fans on and before it fades turn off for a min or so then back on and works ok but a nightmare to try and warm car...any ideas??

 

Sounds like the blower motor bearings have failed. After they have been spinning for a bit they heat up and seize.

 

Like Richie said.

 

Cheer Richie, out she come then!!!