Rear blower motor resistor??

[VikingTrad3r]

2006 yukon xl denali

rear blower motor is surging.

it blows the correct temp but its surging its speed.

anybody?

 

[retiredsparky]

You could try disconnecting the battery for 15 minutes. Sometimes removing power resets modules. Not a likely repair, but worth trying.

 

[JonnyTahoe]

2006 yukon xl denali

rear blower motor is surging.

it blows the correct temp but its surging its speed.

anybody?

 

[UmmScott]

does this happen in both manual and automatic modes?

If its only in automatic mode, I would definitely check the cabin air temp sensor. Cabin air temp and coolant temperature are the 2 main inputs to the HVAC control head for running the blower speed in auto mode. It keeps the blower pretty slow till coolant temp comes up then itll ramp it up until the cabin temp gets closer to the set temperature on the control head.
The cabin air temp sensor is in the headliner right above your head in the drivers seat. No, thats not a microphone, its a temp sensor with a fan pulling air over it

If its doing it in manual mode (you're setting a specific fan speed) then there is something else going on. Could be a bad speed module, bad blower motor, or control head.

 

[JonnyTahoe]

does this happen in both manual and automatic modes?

If its only in automatic mode, I would definitely check the cabin air temp sensor.

My front blower motor Surge issue got worse. I removed the bottom blower motor cover and decided to start with replacing the Resistor first and see if that is the problem. The Resistors for the ''Auto Climate Control'' are not cheap. My local auto stores had all of the common Resistors in stock but not the Resistor for the Auto Climate Control. I called my local GM Dealership and they had one is stock. It's mounted with two small screws next to the blower motor with two wires (Blk and Purple) going to the back of the blower motor.

 

[JonnyTahoe]

I just replaced the front Auto Control Blower Resistor with a Brand New AC Delco Resistor GM P/N 1625-0785. This Resistor and P/N are only for 00-02 model years with the Auto Climate Control. Seems GM changed the Resistor design in 2003.