Defrost door repair
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Joined: Aug 2007
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I managed to get it appart, door broken. It may have broke from a faulty motor or the contol sending the wrong signal. when we ran the motor after removal we found it rotated at least 360 degrees. We do not know if the Heater/AC switch controlls the rotation or the motor has the stops built in. Have orderd new control, will test then.
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Joined: Apr 2005
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From: Old Norte Mexico
I managed to get it appart, door broken. It may have broke from a faulty motor or the contol sending the wrong signal. when we ran the motor after removal we found it rotated at least 360 degrees. We do not know if the Heater/AC switch controlls the rotation or the motor has the stops built in. Have orderd new control, will test then.
The mode door actuator is connected to the heater-
A/C control module through the vehicle electrical system
by a dedicated two-wire take out and connector
of the HVAC wire harness. The mode door actuator
can move the mode door in two directions. When the
heater-A/C control module pulls the voltage on one
side of the motor connection high and the other connection
low, the mode door will move in one direction.
When the module reverses the polarity of the voltage
to the motor, the mode door moves in the opposite
direction. When the module makes the voltage to
both connections high or both connections low, the
mode door stops and will not move. These same
motor connections also provide a feedback signal to
the heater-A/C control module. This feedback signal
allows the module to monitor the operation and relative
position of the mode door actuator and the mode
door. The heater-A/C control module learns the mode
door stop positions during the calibration procedure
and will store a Diagnostic Trouble Code (DTC) for
any problems it detects in the mode door actuator
circuits. The mode door actuator can be diagnosed
using a DRBIII scan tool.
A/C control module through the vehicle electrical system
by a dedicated two-wire take out and connector
of the HVAC wire harness. The mode door actuator
can move the mode door in two directions. When the
heater-A/C control module pulls the voltage on one
side of the motor connection high and the other connection
low, the mode door will move in one direction.
When the module reverses the polarity of the voltage
to the motor, the mode door moves in the opposite
direction. When the module makes the voltage to
both connections high or both connections low, the
mode door stops and will not move. These same
motor connections also provide a feedback signal to
the heater-A/C control module. This feedback signal
allows the module to monitor the operation and relative
position of the mode door actuator and the mode
door. The heater-A/C control module learns the mode
door stop positions during the calibration procedure
and will store a Diagnostic Trouble Code (DTC) for
any problems it detects in the mode door actuator
circuits. The mode door actuator can be diagnosed
using a DRBIII scan tool.
Thread Starter
Registered User
Joined: Aug 2007
Posts: 6
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Thank you for your help, do not wish to have door break again, so will do all the tests. Thought I could test the motor by connecting it without the door attached. we would be able to tell if the motor reacted properly to the selector control. If the motor rotates 360 while not connected to the door, what will prevent it from doing that once I install a new door. I dont understand how the moter will learn a position. How do we do the calibration procedure? Is the DBR111 scan tool the one used by dealer to check all codes?
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