Blower Motor Resistor

This procedure covers removal and replacement of the blower motor resistor/power transistor, which controls HVAC fan speeds in the 2016-2021 Honda Civic with 1.5L turbo engine.

Warnings

Tools required

Parts

• Blower motor power transistor/resistor × 1 — Honda 79330-TBA-A01 or equivalent

Preparation

1. Turn the ignition off and remove the key/fob from the vehicle
2. Set the parking brake and ensure the vehicle is on level ground
3. Allow HVAC system to cool if recently used (minimum 15 minutes)
4. Open passenger door fully for comfortable access to glove box area

Procedure

1. 1

   Remove glove box contents and damper
   Open the glove box and remove all contents. Locate the damper arm on the right side of the glove box. Squeeze the damper arm to disconnect it from the glove box door by compressing the retention clip.
2. 2

   Release glove box stop tabs
   With the glove box open, locate the stop tabs on both left and right sides of the glove box. Squeeze the sides of the glove box inward to release these stop tabs from their slots, allowing the glove box to swing down past its normal open position.
3. 3

   Lower glove box for access
   Carefully lower the glove box downward to expose the blower motor housing area behind it. The glove box will hang freely from its hinges. Use a work light to illuminate the area behind where the glove box was located.
4. 4

   Locate the blower motor resistor
   Behind the glove box opening, locate the blower motor resistor/power transistor on the passenger side of the blower motor housing. It is a rectangular component with a wire harness connector and cooling fins, typically mounted with 2-3 screws on the side of the HVAC housing.
5. 5

   Disconnect electrical connector
   Locate the electrical connector attached to the blower motor resistor. Press the locking tab on the connector while pulling it straight away from the resistor to disconnect. Do not pull on the wires themselves.
6. 6

   Remove resistor mounting screws
   Using a Phillips screwdriver, remove the mounting screws securing the blower motor resistor to the HVAC housing. There are typically 2-3 screws. Keep track of these screws as they are small and may be difficult to retrieve if dropped.
   Torque spec

   Resistor Screws2 Nm (1.5 lb-ft)
7. 7

   Remove old resistor
   Carefully pull the blower motor resistor straight out from the HVAC housing. The resistor has cooling fins that insert into the housing, so pull it directly outward to avoid bending the fins. Inspect the old resistor for signs of burning, melting, or heat damage.
8. 8

   Inspect mounting area
   Before installing the new resistor, inspect the mounting area on the HVAC housing for debris, damage, or signs of overheating. Clean any debris from the mounting surface and ensure the opening is clear. Check that the rubber seal or gasket area is clean and undamaged.
9. 9

   Install new blower motor resistor
   Align the new blower motor resistor with the mounting holes and opening in the HVAC housing. Ensure any rubber seal or gasket is properly positioned. Push the resistor straight into the housing until it seats flush against the mounting surface, with the cooling fins properly inserted into the housing.
10. 10

    Install and torque mounting screws
    Install the mounting screws by hand, threading them carefully to avoid cross-threading. Once all screws are started, tighten them in a cross pattern to 2.0 Nm (1.5 lb-ft) using a torque wrench. Do not overtighten as this may crack the plastic housing.
    Torque spec

    Resistor Screws2 Nm (1.5 lb-ft)
11. 11

    Reconnect electrical connector
    Align the electrical connector with the terminal on the blower motor resistor. Push the connector straight onto the resistor terminal until you hear or feel a positive click, indicating the locking tab has engaged. Gently tug on the connector to verify it is securely locked.
12. 12

    Reinstall glove box
    Lift the glove box back up into its normal position. Push the sides outward slightly and guide the stop tabs back into their slots on both sides. Reconnect the damper arm to the glove box by snapping it back into position on the right side.

Reassembly

1. Ensure glove box operates smoothly and stops at the correct open position
2. Verify damper provides proper resistance when opening the glove box
3. Replace any items removed from the glove box

Verification

• Start the vehicle and turn on the HVAC system
• Test all blower motor speeds (low, medium-low, medium-high, and high) to verify proper operation at each setting
• Listen for any unusual noises from the blower motor that might indicate improper resistor installation
• Verify that air flow increases appropriately with each fan speed setting
• Check that the blower motor turns off completely when the fan control is set to off position
• Confirm no warning lights appear on the instrument cluster related to the HVAC system

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