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Dan
Dan, Technician
Category: Chevy
Satisfied Customers: 23590
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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2007 tahoe rear blower comes on with key off

Customer Question

2007 tahoe rear blower comes on with key off
Submitted: 1 year ago.
Category: Chevy
Customer: replied 1 year ago.
2007 tahoe rear blower comes on with key off. Both front and rear rectifiers are good along with the connectors.
Expert:  Dan replied 1 year ago.

Hello, my name is***** usually means the blower motor control module has failed, has it been replaced? Thanks.

Customer: replied 1 year ago.
Are you referring to the front or rear? Neither has been replaced
Customer: replied 1 year ago.
This problem mainly happens in the middle of the night. Battery is usually low or dead
Customer: replied 1 year ago.
Actually, I misundersttod. The rear resistor has been replaced but not the front.
Expert:  Dan replied 1 year ago.

Do you have automatic or manual controls? Sorry about the delays in replying. Thanks.

Customer: replied 1 year ago.
Manual
Expert:  Dan replied 1 year ago.

This points toward a problem with the auxiliary blower motor control module. Verify only the black wire has ground, if so replace. Here are replacement instructions. Let me know how it goes or if you have more questions. Thanks.
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https://www.dropbox.com/s/o9ggba9j0mopjq9/aux1.pdf?dl=0
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https://www.dropbox.com/s/iutmzgfcbt8mysk/aux2.pdf?dl=0
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Customer: replied 1 year ago.
I tied to communicate to you that the rear control "module" was replaced at the Chevy dealer.
"Verify only the black wire has ground, if so replace".....please expound on this statement.
Expert:  Dan replied 1 year ago.

This would either mean the control wire which goes between controller and blower motor control module has shorted to ground or controller has failed. You can see if blower shuts off when removing the 10 amp hvac fuse in location 38 of fuse box under hood, if it shuts off when removing fuse then the hvac module/controller has failed. If it doesn't shut off then the control wire which is dark green wire. Let me know how it goes or if you have more questions, thanks.

Customer: replied 1 year ago.
Should I assume this test must take place during the condition when the blower is running with the ignition is turned to off? If I were to clip the dark green control wire (as a test to see if it eliminates the condition) would that prove a short?
Expert:  Dan replied 1 year ago.

Yes, do testing with key off during problem. Clipping the dark green wire wouldn't really prove anything because it wouldn't tell us if wire is shorted to ground or if controller is internally shorted. Remove the 10 amp fuse in location 38, if it shuts off then replace controller. If not then it sounds like wire is shorted to ground and will need to be replaced. Let me know how it goes, thanks.

Customer: replied 1 year ago.
That is to say, clipping the dark green wire prior to the condition happening. This condition is very intermittent. The rear blower runs as it should when the condition is not active.
Expert:  Dan replied 1 year ago.
You will need to remove fuse next time problem happens, if it shuts off replace controller. If not, run a new wire. Let me know if you have more questions, thanks.

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