Engine Size: 4.2
Refrigerant Type: r134
Country of Origin: United States
The A/C fan or blower on my 2007 Buick Rainier is not blowing when selected, begins to blow after driving around for a while, stays on after the car is turned-off. I checked the A/C fan motor and it does work (hooked up directly to battery). While I had it apart it began to spin but Climate Control unit did was not able to regulate speed and remained spinning for several minutes after the car was shut down.
I think it might be the Climate Control Unit or the Blower Motor Control Unit. Does anyone have any insights into narrowing down what what it might be?
When it is not working, measure the voltage across the motor (with everything plugged in and turned on). If you have voltage but it doesn't turn, the motor must be bad. Worn out motors become intermittent at first.
If you don't have voltage across the motor, I think most late GMs have a power module controlling the ground side of the motor. If that is how it is and the module is bad, you would have battery voltage on both leads of the motor to ground, but no current flowing through the module. Which would also happen if the control panel were not driving the module, but the module is more likely. Also look for burnt connections on the module plug, that would mean you need to replace both the plug and the module.
"voltage across the motor" means put your voltmeter probes into the back of the motor plug, one on each wire, while it is plugged into the motor. If you have voltage in that test though the motor doesn't turn, motor is bad.
Its difficult to state from your posted symptoms without actually being there. If the motor runs constantly with the key off, definitely a shorted blower control module, but you say yours is shutting down after a period.
With automatic climate control and even manual control on GM vehicles, using soft touch controls, no more real switches, all fire commands to either the BCM or even a separate MVAC computer module, OS is stored in flashram.
Seems the first try to to your your ram reflashed, can't do that a home, have to see your dealer.
Are you sure your "afterblow" feature is not turned on?... GM did this a few times to avert bacteria growth on your evap core due to moisture. The "afterblow" could be commanded on by the Tech II if the smelly evap was ever a complaint- many conditions had to be met - and the owner had to be informed that everything was okay- that his blower would run a few minutes after he removes his keys.
There were also hang -on after blow kits available to avert smelly evaps-- sure yours does not have one? Have you had the vehicle since it was new?
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
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