03 tahoe blower Moyer stays on all the time

03 tahoe with auto climate controls the blower motor stays on all the time key on key off, I checked at the blower itself and the plug has one of the three wires that shows 12volts constant , I have disconnected the climate control in the dash seeing if that was making it come on but still on all the time so I ruled out that head unit was causing it I’ve seen several suggestions that replacing the blower resistor for the manual controls but I’m at a lost since it seems to have power all the time at the harness coming into the blower with the harness unplugged

Blower motor resistor?

the resistor is where the blower power harness comes from, so if the resistor is bad it's shorted and not cutting the power like it should, over time they melt from heat and i'm surprised the darn things haven't burnt cars up

Doubeleive said:

the resistor is where the blower power harness comes from, so if the resistor is bad it's shorted and not cutting the power like it should, over time they melt from heat and i'm surprised the darn things haven't burnt cars up

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ikr?

Here let's put something that dumps extra power as heat in there, let it be cooled by the air from the thing it's regulating.

Why the MFRs don't use a pwm design that's been in power supplies for decades is beyond me

Your fan control module is broken. this sends 12 volts continuously to the fan. it is possible that the fan is also going bad, because as it starts to short out internally, it destroys the fan control module. Rockauto.com or any auto parts store has them

Wbzautocustomiz said:

03 tahoe with auto climate controls the blower motor stays on all the time key on key off, I checked at the blower itself and the plug has one of the three wires that shows 12volts constant , I have disconnected the climate control in the dash seeing if that was making it come on but still on all the time so I ruled out that head unit was causing it I’ve seen several suggestions that replacing the blower resistor for the manual controls but I’m at a lost since it seems to have power all the time at the harness coming into the blower with the harness unplugged

Click to expand...

This just happened to me the other night. I pulled off the rear side panel to get access to the blower motor and disconnected the power plug to the motor.

Not saying the controller isn't bad but when in my shops years back I remember replacing resistor to fix this type of problem. May be both and if it was mine I would replace both to help insure that it is fixed and not staying on when out of vehicle and maybe cause a fire from an overheated motor.

Doubeleive said:

the resistor is where the blower power harness comes from, so if the resistor is bad it's shorted and not cutting the power like it should, over time they melt from heat and i'm surprised the darn things haven't burnt cars up

Click to expand...

Yep. Since the OP disconnected the dash control it seems like it would make sense to check the resistor first. Resistor failure in these is very common.

Thats how the system works in these.

The power module (its not a resistor pack since you have auto climate control) will have 12 volts at it no matter what 24/7.

It receives a Pulse width modulated signal from the climate control head (on that tiny purple wire) and that tells the module what speed to run the blower.

Replace BOTH the module and the blower at the same time. Use OE parts here. The Dorman or aftermarket parts are crappy and you'll lose speeds with the power modules.
Aftermarket blowers tend to be loud/noisier than the ACdelco originals.

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Only reason to say that its a power module is if u waltz into o'reillys or wherever and talk to some parts dude and say resistor, thats what he'll give you since its so much cheaper.
LOL

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