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HVAC Stepper Motor Replacement
 
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Pelican Technical Article:

HVAC Stepper Motor Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$200

Talent:

****

Tools:

Phillips screwdriver, plastic prying tool

Applicable Models:

BMW 525i/xi Sedan (2004-07)
BMW 528i xDrive Sedan (2009-10)
BMW 528i/xi Sedan (2008-10)
BMW 530i/xi Sedan (2004-07)
BMW 530xi Wagon (2006-07)
BMW 535i xDrive Sedan/Wagon (2009-10)
BMW 535i/xi Sedan (2008-10)
BMW 535xi Wagon (2008)
BMW 545i Sedan (2004-05)
BMW 550i Sedan (2006-10)
BMW M5 Sedan (2006-10)

Parts Required:

Stepper motors

Hot Tip:

Be careful not to damage HVAC flaps

Performance Gain:

Replace faulty stepper motors

Complementary Modification:

Replace blower motor and resistor

The HVAC stepper motors are attached to the heater housing and responsible for directing air flow by moving air flow flaps. There are a total of nine stepper motors, which only three are accessible without removing the heater housing. This tech article will cover the three accessible stepper motors, the remaining 6 will be covered in a heater housing tech article. The accessible stepper motors are responsible for the center compartment duct, the left dashboard vent and the front air distribution flap. If one of these ducts is not functioning correctly, remove the stepper motor and inspect the flap shaft for damage. They can break, leaving the flap detached from the stepper motor. Remove the stepper motor you suspect has an issue. Then rotate the flap with a flathead screwdriver. You should be able to hear the flap move position as you rotate the shaft.

Remove the IHKA control panel, radio and seat heat controls. See our tech article on IHKA control panel, radio and seat heat controls replacement.

Remove the right and left side lower dashboard trim. See our tech article on lower dashboard trim replacement.

With the radio removed, remove the component mounting bracket Phillips head screws (red arrows).
Figure 1

With the radio removed, remove the component mounting bracket Phillips head screws (red arrows).

Then, remove the component mounting bracket from the dashboard.
Figure 2

Then, remove the component mounting bracket from the dashboard. Note the routing and position of the wiring harnesses before removing. This will help to get things back in the right place when reinstalling.

Center Compartment Flap: Remove the center console.
Figure 3

Center Compartment Flap: Remove the center console. See our tech article on center console replacing. Working at the center compartment duct, unclip the two retaining clips (red arrows). Press the center of the clip and pull the bottom of the clip off the duct to detach it.

Center Compartment Flap: Next, slide the duct down far enough to access the stepper motor electrical connector.
Figure 4

Center Compartment Flap: Next, slide the duct down far enough to access the stepper motor electrical connector. Pull the electrical connector (red arrow) straight out of the stepper motor to remove the connector.

Center Compartment Flap: Slide the duct down.
Figure 5

Center Compartment Flap: Slide the duct down. Then remove duct from dashboard, feeding the top out first.

Center Compartment Flap: To replace the stepper motor, press the release tab (red arrow) and remove it at an angle (blue arrow) until it is detached.
Figure 6

Center Compartment Flap: To replace the stepper motor, press the release tab (red arrow) and remove it at an angle (blue arrow) until it is detached. Inspect the flap shaft and stepper motor drive (green arrows). Be sure the two are aligned when reinstalling. Do not try to move the stepper motor drive manually. If needed, move the flap shaft to align it with the stepper motor drive. Reverse the steps to reassemble. Feed the stepper motor into the flap shaft at an angle. Then press it into place until two snaps are heard.

Left Dashboard Vent: With the center compartment duct removed, remove the left side air duct (red arrow).
Figure 7

Left Dashboard Vent: With the center compartment duct removed, remove the left side air duct (red arrow).

Left Dashboard Vent: To remove the duct, lift it up and pull the bottom out.
Figure 8

Left Dashboard Vent: To remove the duct, lift it up and pull the bottom out. Then slide it toward the right side of the vehicle. Rotate the bottom of the duct up, while disconnecting it from the under dash duct. Reach up from the left side footwell if needed to detach the opposite side of the duct. Note the duct's removal position for reinstallation.

Left Dashboard Vent: Working in the left side footwell, detach the wiring harness from the mount (red arrow).
Figure 9

Left Dashboard Vent: Working in the left side footwell, detach the wiring harness from the mount (red arrow). Then, disconnect the stepper motor electrical connector (blue arrow) by pulling it straight out.

Left Dashboard Vent: To replace the stepper motor, press the release tab (red arrow) and remove it at an angle until it is detached.
Figure 10

Left Dashboard Vent: To replace the stepper motor, press the release tab (red arrow) and remove it at an angle until it is detached. Inspect the flap shaft (blue arrow) and stepper motor drive. Be sure the two are aligned when reinstalling. Do not try to move the stepper motor drive manually. If needed, move the flap shaft to align it with the stepper motor drive. Reverse the steps to reassemble this stepper motor. Feed the stepper motor into the flap shaft at an angle. Then press it into place until two snaps are heard.

Left Dashboard Vent: This duct (red arrow) is a pain.
Figure 11

Left Dashboard Vent: This duct (red arrow) is a pain. Most of the time when I get to it, the stepper motor has it in the raised position. Then when removed, it drops, making alignment hard. Don't worry, I have devised a trick to get it back in. First confirm the stepper motor drive and flap shaft are not aligned.

Left Dashboard Vent: Then lift the duct up and hold it.
Figure 12

Left Dashboard Vent: Then lift the duct up and hold it. Jam a plastic prying tool between the duct and the housing to prop the duct open. This will hold it in place when installing the stepper motor.

Front air flap: With the center compartment duct removed, remove the right side air duct (red arrow).
Figure 13

Front air flap: With the center compartment duct removed, remove the right side air duct (red arrow). First, disconnect the blower motor electrical connector (blue arrow). Squeeze the release tabs and pull the lower portion of the connector out (top inset). To remove the duct, lift it up and pull the bottom out. Then slide it toward the left side of the vehicle. Rotate the bottom of the duct up, while disconnecting it from the under dash duct. Reach up from the right side footwell if needed to detach the opposite side of the duct. Note the removal position for reinstallation.

Front air flap: To replace the stepper motor, press the release tab (blue arrow) and remove it at an angle until it is detached.
Figure 14

Front air flap: To replace the stepper motor, press the release tab (blue arrow) and remove it at an angle until it is detached. Once removed from the housing, disconnect the electrical connector by pulling it straight out. Inspect the flap shaft (green arrow) and stepper motor drive. Be sure the two are aligned when installing. Do not try to move the stepper motor drive manually. If needed, move the flap shaft to align it with the stepper motor drive. Reverse the steps to reassemble the stepper motor. Feed the stepper motor into the flap shaft at an angle. Then press it into place until two snaps are heard. Reassemble the dashboard and instrument panel trim. Check and clear any fault codes that may have been set.









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Page last updated: Fri 12/2/2016 02:37:57 AM