Heater fan dead?

[jeff in co]

My fan use to work intermittedly and now nothing. The PO installed a new fan from Napa and said it works "sometimes". When I got the truck, he had a bad ground right at the motor. Fixed that and the heater worked fine. Now after a few months, it has consistently gotten worse.

I picked up a new relay yesterday but still nothing. I took a meter tester and checked the voltage from ground to the single, purple wire going to the motor and I get 12V regarless of the fan speed switch in the A/C controller.

Should this voltage change due to the fan speed or should it always remain at 12V?

I am assuming there is a warranty on the fan from Napa so I may just have them give me a new one. It's starting to get cold and need some heat!

 

[diesel4me]

I'd run a hot wire right to the blower motor to see if its working right...if it does run at full speed hot wired,then I'd suspect a wiring defect or possibly the resistor for the different speeds has crapped out,its not uncommon..you'll only see 12V at the purple wire no matter what speed you have the switch set too,as the plug for the blower motor is before the resistor (actually it plugs right onto it,on the 73-87 trucks)..if your truck is newer,my advice might not be correct,I haven't had any 88 up trucks to fool with yet...(and probably wont,I prefer old iron)..

 

[jeff in co]

Yea, mines an 89 Blazer. I'll try out just giving it some straight 12V juice and see if it runs or not. I found the receipt from the PO and it's a lifetime warranty. Hope this is it.