Blower motor runs key off

Tiny
TZUMMY
  • MEMBER
  • 1990 CADILLAC ELDORADO
  • 4.5L
  • V8
  • FWD
  • 40,000 MILES
The blower motor will not shut off. Cannot find a relay which I am sure is stuck.
Saturday, August 12th, 2017 AT 6:23 PM

1 Reply

Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
My research shows that there is no actual relay for the blower. What you are looking for is called a power module. According to ProDemand:

"The power module controls the operation of the compressor clutch and the blower motor. It is located on top of the evaporator assembly in the HVAC air stream.

The power module receives the blower drive signal from the programmer and amplifies the signal to a strong output voltage proportional to the input. The power module is also transistorized, and can provide variable blower speeds.

The power module also receives a drive signal from the ECM, which is used to engage the A/C compressor clutch. The BCM controls the cycling of the clutch based on its inputs"

I cannot seem to find a diagram that better explains where to find it. According to some, it may be under the hood in the blower assembly box (which should be on the firewall).
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Saturday, August 12th, 2017 AT 7:46 PM

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