2007 Tahoe LTZ, Blower fan doesn't work.

[mike tamm]

My Tahoe with the auto HVAC system, won't turn on the blower.
The display shows the low to high adjustment of the blower but it doesn't start or change the blower. I disconnected the plug at the resister and applied power and the blower motor works. I checked fuses and all were good. I replaced the resister and no difference. I checked for codes and there are none. With the scanner I checked the HVAC data.
A/C permission, all "normal".
HVAC Door positions, all are "*"
HVAC Sensors, all "32 degrees"
Inputs, all "Inactive"

To me its acting like a module is bad. Can anyone direct me to which module it might be and how to test it? Also where this module is located?

Thanks,
Mike

 

[Doubeleive]

have you verified voltage to the resistor?, what resistor did you buy? I don't think there is another module on these trucks between the ac control and resistor. if the sensor in the headliner is funky that could "maybe" cause a problem but not sure on that. reading about it in the past I think it has caused problems with getting hot/cold to work properly so that may not directly affect the blower motor coming on at all.

 

[mike tamm]

I did verify I have 12v+ at the power wire at the resister

 

[Doubeleive]

I did verify I have 12v+ at the power wire at the resister

I would suspect either a bad resistor or the control head has gone funky then, if you can I would try another resistor first and/or try ohm testing from the resistor harness to the control head, not sure what it should be reading but I would assume if you have your meter connected and you adjust the fan speed on the control head you should see the range change on the meter that range may be very small so I would try another resistor first.

 

[mike tamm]

I already replaced the resistor, are you saying to replace it again? Bad part?
I really don't think its the resister because the checks from the scan tool show that a lot of the inputs to the system are not reading anything and shutting the system down.

 

[Fless]

I did verify I have 12v+ at the power wire at the resister

When you tested the 12v at the power connector did you use the ground in the wire, or use a different location for the ground? If different ground, like a body bolt, test that 12v using the ground in the harness, if there is one.

 

[Doubeleive]

I already replaced the resistor, are you saying to replace it again? Bad part?
I really don't think its the resister because the checks from the scan tool show that a lot of the inputs to the system are not reading anything and shutting the system down.

YES exchange it

 

[mike tamm]

When I checked the power at the resistor, I used a chassis bolt so I just went out to the truck to test again to the resistor ground and got 12v+.
It's getting cold here in Michigan, so I had wires and a toggle switch hooked up so I could get heat, defrost and cooling. Just for fun I unhooked my bypass wires and hooked up the resistor again, and started the truck and it works! I can turn the fan up and down with the controls. I hooked up the scan tool and all the readings are back to normal? Why did it all of a sudden correct itself?

 

[Fless]

You probably moved a wire that is marginal, maybe rubbing on something, or the connector wasn't making a good electrical connection and "working" it may have made the connection. I'd be looking at the harness, the connector, and anything else around that area that could affect it.

 

[Geotrash]

You probably moved a wire that is marginal, maybe rubbing on something, or the connector wasn't making a good electrical connection and "working" it may have made the connection. I'd be looking at the harness, the connector, and anything else around that area that could affect it.

This is my bet too. I usually use electronics cleaner (not electrical parts cleaner) on connectors on an older car before I put them back together.


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[mike tamm]

Thanks for the help.

 

[Joseph Garcia]

Thanks for the help.

Thank you for getting back and advising us that it is now working, and perhaps caused by a spurious electrical connector issue. Knowledge is power, and you've increased our collective knowledge base.

 

[2011SSVTahoe]

I had the wire that went from the resistor to the blower motor burn up. Had to get a new wire.

https://www.partsgeek.com/gbproduct...uOqlFWRTCnHCGjHX6sKQUhpF5D9PTqEgaAkanEALw_wcB

Other than that I found reseating the Junction Block fixed a lot of internal electrical issues