Diagnosis And Testing - Blower Motor

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 conditions that customer is complaining of 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 system)
   • Fresh or Recirculation
   • Time of day or when occurs (first starting vehicle, after driving distance, etc)
   • Auto / manual mode
2. Check vehicle with same settings as customer complaint. Vary blower speed from minimum to maximum to see if you can detect a change in the noise throughout the speed settings.
3. Does noise seem abnormal? (Ticking, Grinding, Whirring, Whistling, Howling, Excessively loud, etc)
   • Yes -> Go to 4.
   • No -> Return vehicle to customer and/or ask for additional information
4. Compare noise level to similar vehicle with 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 6
6. Remove blower motor from vehicle and inspect fan blades for foreign material, or proof of contact with 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 10
   • No -> Go to 9
9. Was any foreign material present?
   • Yes -> Remove material and reinstall blower motor. Go to step 2
   • No -> Go to 10
10. Replace blower motor with new service part and go to step 2.
    NOTE:

    Inoperative/Intermittent 

1. Confirm conditions that customer is complaining of inoperative issue.
   • Fan speed setting
   • Time of day or when occurs (first starting vehicle, after driving distance, what kind of driving (off road, city), etc)
   • Auto / manual mode - Was temperature matching automatic? Manual?
2. Compare conditions from #1 in a similar vehicle as customer complaint.
3. Was customer Blower Motor found to be inop or have intermittent operation?
   • Yes -> Go to 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 5.

   Courtesy of CHRYSLER GROUP, LLC

5. Check power and ground connections at blower motor (example is shown above; confirm pinout with customer vehicle schematic).
6. Check resistance from Pin 1 to known good ground.
7. Was resistance <3 ohms?
   • Yes -> Go to 8
   • No -> Go to 5, check if repair needed to the ground circuit
8. Set Key to RUN, with the engine off and blower motor turned on, check voltage with multimeter from Pin 3 to known good ground.
9. Was voltage approximately same as battery voltage?
   • Yes -> Go to 10
   • No -> Check power supply circuit, including wiring from blower motor relay and relay itself, to find source of low voltage.
10. Set Key to RUN, with the engine off and blower motor turned on, check voltage with multimeter from Pin 2 to known good ground.
11. Was PWM (Pulse Width Module) duty signal found and changed with different blower speed settings, see below for test method?
    • Yes -> Go to 12
    • No -> Check A/C-Heater Module for source of missing PWM duty signal.
12. Replace blower motor with 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 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 3
    • Variable does not react to fan speed setting changes? -> Go to 4
15. Verify response or change in actual air flow coming out from the vents when blower speed setting is changed.
    • Is air moving and blower speed reacting as expected? -> Go to 4
    • No blower actual response to fan speed setting changes? -> Verify HVAC harness and blower per Intermittent/Inoperative procedure.
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.
    • Variable does not change per expected fan speed setting? -> Replace HVAC control.