Blower Motor Control Module

This procedure covers the removal and replacement of the blower motor control module (also called blower motor resistor or power module) on a 2007 Ram 3500 with 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Blower motor control module (resistor/power module) × 1 — Use OEM specification or equivalent
• Electrical connector dielectric grease × 1 — Optional but recommended

Preparation

1. Park vehicle on level surface and turn off engine
2. Allow HVAC system to cool for at least 30 minutes if recently used
3. Turn ignition to OFF position and remove key
4. Open passenger side door for access

Procedure

1. 1

   Locate the blower motor control module
   The blower motor control module is located on the passenger side of the vehicle, inside the HVAC housing below the glove box area. It is mounted on the side of the blower motor housing. You may need to get on your knees or use a flashlight to see it clearly - it will have a wiring harness connector attached to it.
2. 2

   Remove lower dash panel if necessary
   On some configurations, you may need to remove the lower dash panel or silencer panel below the glove box for better access. If present, locate the plastic push-pin fasteners or screws holding the panel and carefully remove them. Use a panel trim tool to release any clips. Set the panel aside.
3. 3

   Disconnect the electrical connector
   Locate the electrical connector attached to the blower motor control module. Press the locking tab on the connector and pull it straight off the module. You may need to wiggle it gently while pulling. The connector may be tight due to heat cycling over the years.
4. 4

   Remove the module mounting screws
   Using the correct driver (commonly a 5.5mm nut driver or T20 Torx on Chrysler HVAC modules — verify the actual fastener), remove the two screws securing the blower motor control module to the HVAC housing. The screws are typically located on either side of the module. Support the module with your hand as you remove the second screw to prevent it from falling.
5. 5

   Remove the blower motor control module
   Pull the module straight out from the HVAC housing. It should slide out of its mounting position. Note the orientation and position of any foam seals or gaskets that may be present between the module and housing - these must be reused or replaced.
6. 6

   Inspect the connector and wiring
   Examine the electrical connector terminals for signs of overheating, melting, corrosion, or burn marks. Also inspect the blower motor housing opening for debris or damage. If the connector shows heat damage, it should be replaced along with the module to prevent future failures.
7. 7

   Install the new blower motor control module
   Position any foam seals or gaskets onto the new module in the same orientation as they were on the old unit. Align the new module with the mounting holes in the HVAC housing and slide it into place, ensuring it seats fully against the housing.
8. 8

   Install the mounting screws
   Install the two mounting screws (matching the size removed earlier) and tighten them snugly. Do not overtighten as the plastic housing can crack. Tighten just until the module is firmly secured against the housing without gaps.
9. 9

   Reconnect the electrical connector
   Apply a small amount of dielectric grease to the terminals of the electrical connector if desired to protect against corrosion. Push the connector firmly onto the new module until you hear or feel it click into place. Ensure the locking tab engages properly.
10. 10

    Reinstall lower dash panel
    If you removed a lower dash panel or silencer panel in step 2, reinstall it now by aligning the clips and pressing it into place, then installing any screws or push-pin fasteners that were removed.

Reassembly

1. Ensure all electrical connections are secure and fully engaged
2. Verify all dash panels are properly reinstalled and fasteners are tight
3. Double-check that no tools or parts were left in the work area

Verification

• Turn the ignition to the RUN position without starting the engine
• Turn on the HVAC system and test the blower motor at all speed settings (Low, Medium-Low, Medium-High, and High)
• Verify the blower motor operates smoothly at each speed without unusual noises
• Confirm airflow changes appropriately with each speed setting
• Listen for any air leaks around the module installation area - all air should come through the vents
• If the blower motor still does not work properly, verify the connector is fully seated and check for blown fuses in the fuse panel

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle