blower just runs on its own even when the key is out?

1999 CADILLAC DEVILLE
90,000 MILES
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MKEE19
  • MEMBER
  • 2 POSTS
Should I be looking for a new blower motor or does this sound like a short of some kind when blower just runs on its own even when the key is out?

A few weeks ago my wife's car wouldn't start. I tried to crank it and the blower turned on by itself, but the car was not starting. I jumped the car, and the blower just ran. I couldn't turn it off. I switched b/t hot , cold, and defrost and it just ran.

I turned the car off after about 10 minutes of letting it run and the blower was still going. The next morning the battery was dead, so I figured the blower running killed the battery. I jumped it again and this time the motor didn't run at all no matter what I did. I wiggled and checked fuses and wasn't sure which controlled it but it still didn't turn on. She drove it for about a week and then one day it wouldn't start again.

When I put the key in and tried to start it, the blower turned on again, so I figured it turned on sometime during the night and drained the battery again. I have not jumped it again since then. I think the blower is working, but maybe a short or something is causing it to run on its own.
Nov 12, 2011 at 10:17 AM
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DRCRANKNWRENCH
  • ✓Experienced Mechanic
  • 3,380 POSTS
There is a blower motor resistor module that may have failed and caused the problem.

It is located under the center console near rear blower motor.

Dis-connect it and see if the blower motor stays off. If so, replace the resistor module.
Nov 12, 2011 at 4:21 PM
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CADIEMAN
  • ✓Experienced Mechanic
  • 3,544 POSTS
The blower motor module is bad.its on top of the a/c case under the hood.it has 2 connectors. its bolts into the a/c case with 3 7mm screws.the module is bolted into the a/c case because is needs to stay cold. You'll need to remove the power wire from the motor to stop the draw. Until you can replace the a/c blower module.
Nov 14, 2011 at 1:11 PM
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MKEE19
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Ok, so I should not be looking anywhere on the actual blower itself? Just so I understand properly, you are not talking about the connector on the rear of the blower correct? Is the a/c case located near the firewall under the hood as well? Is this a part that I can purchase separately.

I've asked for a "blower control modulator" b/c I had a friend say that's what it sounding like caused the problem, but when I went around looking for one, no auto-part stores had them. Is this something I can only find at the dealer.
Nov 16, 2011 at 2:38 AM
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FACTORYJACK
  • ✓Experienced Mechanic
  • 4,159 POSTS
There is no blower resistor, or power module for this vehicle. The a/c programmer, which is the control module for HVAC functions, is the speed controller for the blower motor.
Nov 16, 2011 at 8:14 AM
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