Blower motor

[Dennis Wilkie]

I just noticed my blower sounds like it's always on even when it's not supposed to be. My fan won't actually kick on and blow unless I switch it on high, but it sounds like there's always something running in that general area even when it's off, and the heater/ac lights are weirdly selective on when they want to illuminate. Any ideas on what that might be?

 

[Schurkey]

WHAT VEHICLE?

When my '97 K2500 had no blower speeds except "high", the blower resistor assembly had a failed thermal fuse. The thermal fuse is "not replaceable" separately, so a new resistor assembly was obtained from the Treasure Yard, which fixed the lack of lower speeds.

Beyond that, I have no idea what might be running over there. A failed air-door actuator?

My '88 K1500 has the goofy electro-flourescent-thingamajig display for the heater/AC. The thing doesn't work as often as it does; and I've had it apart twice to re-flow solder on the display board (which absolutely, positively fixes the problem...for about six months.) I finally discovered a spot on the front, which if I apply pressure with my thumb, revives the display for minutes or hours.

 

[98 Nitro]

When mine was acting up last year in winter I replaced the fan switch, and while out replaced the 20yr old finicky bulbs. Sometimes you have to replace the whole panel, or as Schurkey said the resistor.

 

[Dennis Wilkie]

It's a 92 k1500 4x4, aside from the engine transmission and rear end. Forgot to add that part, lol. I had a feeling it was in the general area of the actuator or a stuck vent based on everything i've read from other people having similar problems. I'll probably get out there and see what I can figure out after the power fully drains. Had to reset my ecm for an unrelated issue

 

[Gramps]

Resistor is toast if you’ve lost everytbing but high.
And I think if I remember right gm had it so even when the heater was “off” the fan would still run just a little like half the speed of the low setting, to circulate the air.

 

[Dennis Wilkie]

Switched out the actuators and resistor, and it's doing the exact same thing. No difference whatsoever.

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[east302]

Here are the diagnostics for a 98. The general function is possibly the same for a 92 (resistor plus relay for high speed) so maybe it will help.

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[Schurkey]

Switched out the actuators and resistor, and it's doing the exact same thing. No difference whatsoever.

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Yes, that's the blower resistor assembly.

No, those are not the air door actuators. Those are relays. The air door actuators look like little pianos

 

[Dennis Wilkie]

I'm well aware of what the actuators are, and yes I changed both of them. Those were just some extra relays I grabbed from the same truck just in case

 

[superdave]

I fought an on again off again war with my fan and switch for years. Finally figured out that the wiring harness that plugs into the switch had overheated and melted/softened enough to move the pins and make the connection iffy. I have replaced the fan switch twice, put a whole new control panel in, replaced the blower motor (it was bad), replaced the relay and resistor. Finally figured it out because while I was getting 12v at the fan when checking with a meter, it would barely make the circuit tester light up at all. The connection was bad.