1991 suburban blower motor

I have a 1991 suburban and the blower for the heater/defrost/air doesn't work.
I checked and there is power to the blower so I changed the blower motor. The low fan speeds didn't work. The high speeds did work but only shortly. Now I'm back to square 1 with no blower. I checked underdash fuses and they were fine.
I checked the circuit in the wires to the dash fan controller and 3 of the 4 wires have good power(orange wire). Is that normal?

I checked the circuit under the hood at the blower motor resistor. The fan worked breifly and then went off. Is the resistor bad? is the dash switch bad? or do i have a broken circuit?

It is possible that the resistors are blown. My dad has a 93 1500 and the same thing happend to his and it was a blown diode. My 2000 silverado as well did the same thing , no lower speeds only high. The blower motor was almost not turning at all cause it was seized so bad and this extreme load on lower speed settings blew the resistors.

Okay, so now I'm interested. How did you replace the blown diodes? Do you mean fuses? Did you replace them from the fuse box on the left inside of the dash, or did you replace them in the engine compartment?

I have a '97, and mine is doing the same thing - heater blower works on high, but no other speeds. I thought it was a switch - replaced it, and no dice. I did have a fan issue some months ago, but thought I fixed it when I found the instructions to the dash assemply in the fan (bussing/whistling sound when the motor was running) - guess maybe I should have replace the motor and the fuses/diodes, huh!

Anyway, if you could tell me what you replaced, and where it was, I will try that and see if that fixes it. If it does, I'll replace the blower motor as well, just to be safe (hey, it's only 60 bucks and a little time, right?)!

Thanks for any response you can send me!

Sincerely,

Jeff Gates
gatesfam@swbell.net

im also interested i have a 98 sub that experienced a loud noisy blower i took it to the dealer and they said the blower motor was about to seize and it was going to cost 300 to fix. i decided to wait till summer to worry about it, but shortly after that i lost my low and med speeds, now only have high. i went to auto zone and bought the blower for 80 bucks and replaced it my self. not too hard. but when i tried it out i still only have high speed. now what?? i called the dealer he said could be the control head? or resistor? now what and were are these?? and more importantly how much are these? i am a women trying to do it my self, should i even attempt this? PLEASE HELP!

Hi, the resistors create the lower speed settings by burning electricity, which leaves less for the motor.
That is why you now only have the high speed - the resistors probably got burnt out when the fan motor started seizing and drew too much current through the resistors.
I don't know, where they are on your car. Sometimes they are in the duct near the fan to get cooled. Just follow the wires back from the fan motor. 2 wires are from the resistors to the motor, more wires are from the resistors back to the switch. One extra wire for each speed.
Hope this helps, Eggert :bananasmi

I have the same problem.
Replaced the resistor and still nothing.
I have power going into to the resistor(checked with test light) , but have no power coming from the other wires.
I hooked the blower to the battery and it does spin though squeals very bad.
Could the motor going out blow the switch???

Hi, sounds like you found the problem: Bad motor eating resistors.
Take care, Eggert :bananasmi