Diagnosis And Testing

To determine if an open condition exists within the blower motor circuit wiring, it is necessary to disconnect the negative battery cable and check for continuity within the blower motor circuits using an ohmmeter. See Wiring Information for circuit descriptions and diagrams.

1. Confirm the conditions that the customer is complaining of a noise issue.
   • Fan speed setting
   • HVAC mode (Panel, Bi-Level, Floor, Mix, Defrost, temperature setting - both Driver and Passenger set point if Dual Temperature Zone HVAC Unit)
   • Fresh or Recirculation
   • Time of day or when occurs (first starting vehicle, after driving distance, etc)
   • Auto / manual mode
2. Check the vehicle with same settings as customer complaint. Vary the blower speed from minimum to maximum to see if a change in the noise can be detected throughout the speed settings.
3. Does the noise seem abnormal? (Ticking, Grinding, Whirring, Whistling, Howling, Excessively loud, etc)
   • Yes -> Go to step 4  .
   • No -> Return vehicle to customer and/or ask for additional information
4. Compare noise level to a similar vehicle with the same HVAC settings.
5. Can you confirm similar noise on the other vehicle?
   • Yes -> Return vehicle to customer and/or ask for additional information
   • No -> Go to step 6  .
6. Remove the blower motor from vehicle and inspect the fan blades for foreign material, or proof of contact with the HVAC Case, that could be causing fan imbalance (leaves, debris, case markings, rub evidence - black ring on top of fan, etc).
7. Check fresh air inlet and recirculation areas for any foreign material.
8. Was there evidence of Fan to Case contact?
   • Yes -> Go to step 10  .
   • No -> Go to step 9  .
9. Was any foreign material present?
   • Yes -> Remove material and reinstall the blower motor. Go to step 2  .
   • No -> Go to step 10  .
10. Replace the blower motor with a new service part and go to step 2  .

1. Confirm conditions that the customer is complaining of an inoperative issue.
   • Fan speed setting
   • Time of day or when occurs (first starting vehicle, after driving distance, what kind of driving (off road, city), other)
   • Auto / manual mode - Was temperature matching automatic? Manual?
2. Compare conditions from step 1 in a similar vehicle as customer complaint.
3. Was the customer Blower Motor found to be inoperative or have intermittent operation?
   • Yes -> Go to step 4  .
   • No -> Return vehicle to customer and/or ask for additional information
4. Check for any HVAC system DTCs. DTC exists?
   • Yes -> Diagnose and repair per DTC-based diagnostics.
   • No -> Go to step 5  .

   Courtesy of CHRYSLER GROUP, LLC

5. Check the power and ground connections at the blower motor (example is shown above; confirm pinout with customer vehicle schematic).
6. Check the resistance from Pin 1 to a known good ground.
7. Was the resistance <3 ohms?
   • Yes -> Go to step 8 

     .

   • No -> Go to step 5  , check if a repair is needed to the ground circuit

     .

8. Set the Key to RUN, with the engine OFF and blower motor turned ON, check voltage with a multimeter from Pin 3 to a known good ground.
9. Was voltage approximately the same as battery voltage?
   • Yes -> Go to step 10 

     .

   • No -> Check the power supply circuit, including wiring from the blower motor relay and the relay itself, to find source of low voltage.
10. Set the Key to RUN, with the engine OFF and blower motor turned ON, check the voltage with a multimeter from Pin 2 to a known good ground.
11. Was the PWM (Pulse Width Module) duty signal found and changed with different blower speed settings, see below for test method?
    • Yes -> Go to step 12 

      .

    • No -> Check the A/C Heater Module for the source of the missing PWM duty signal.
12. Replace the blower motor with a new service part and repeat step 1 to confirm the motor is functioning as expected.
    NOTE:

    Blower PWM command verification 

13. Connect to the vehicle with a scan tool, read HVAC DTCs.
    • DTCs found? -> proceed in accordance to standard DTC repair action procedures.
    • No DTCs found? -> Go to step 2 

      .

14. Using a scan tool, monitor "Front Blower Speed" on the Data Display tab and verify the response/change of this variable when blower speed setting is changed manually using the knob or touchscreen. (Variable value should increase at higher fan speed settings).
    • Variable changes as expected -> Go to step 3 

      .

    • Variable does not react to fan speed setting changes -> Go to step 4 

      .

15. Verify response or change in actual air flow coming out from the vents when blower speed setting is changed.
    • Air moving and the blower speed reacting as expected -> Go to step 4 

      .

    • No blower actual response to the fan speed setting changes -> Verify HVAC harness and blower per Intermittent/Inoperative procedure above.
16. Using a scan tool, monitor "Front Blower Speed Selected" on the Data Display tab and verify the response/change of this variable when blower speed setting is changed using knob or touchscreen (OFF, Manual 1, Manual 2., Manual 10, AUTO).
    • Variable changes per expected fan speed setting -> Verify HVAC harness and blower per Intermittent/Inoperative procedure above.
    • Variable does not change per expected fan speed setting -> Replace HVAC control.