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Blower Speed Does Not Correspond With Control Setting

BLOWER SPEED DOES NOT CORRESPOND WITH CONTROL SETTING

Blower Speed Does Not Correspond With Control Setting:





POSSIBLE CAUSES
- (C71) Blower motor low driver circuit/(C73) blower motor M2 driver circuit/(C72) blower motor M1 driver circuit/(C70) blower motor high driver circuit shorted to ground
- (C71) Blower motor low driver circuit/(C73) blower motor M2 driver circuit/(C72) blower motor M1 driver circuit/(C70) blower motor high driver circuit shorted to voltage
- (C71) Blower motor low driver circuit/(C73) blower motor M2 driver circuit/(C72) blower motor M1 driver circuit/(C70) blower motor high driver circuit shorted together
- (C71) Blower motor low driver circuit/(C73) blower motor M2 driver circuit/(C72) blower motor M1 driver circuit/(C70) blower motor high driver circuit open
- Blower motor resistor block open
- A/C heater control

Diagnostic Test

1. CHECK IF THE BLOWER MOTOR RUNS WITH THE BLOWER CONTROL IN THE OFF POSITION
Turn the Blower control to the Off position.
Turn the ignition on.

Q: Does the blower motor run?

YES: Go To 2
NO: Go To 3

2. CHECK THE (C71) BLOWER MOTOR LOW DRIVER CIRCUIT, THE (C73) BLOWER MOTOR M2 DRIVER CIRCUIT, THE (C72) BLOWER MOTOR M1 DRIVER CIRCUIT, & THE (C70) BLOWER MOTOR HIGH DRIVER CIRCUIT FOR A SHORT TO GROUND




Turn the ignition off.
Disconnect the A/C Heater Control C2 harness connector.
Disconnect the Blower Motor Resistor Block harness connector.
Measure the resistance of the (C71) Blower Motor Low Driver circuit, the (C73) Blower Motor M2 Driver circuit, the (C72) Blower Motor M1 Driver circuit, and the (C70) Blower Motor High Driver circuit between ground and the A/C Heater Control C2 harness connector.

Q: Is the resistance below 10K ohms on any of the circuits?

YES: Repair all circuits with a resistance below 10K ohms for a short to ground. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the A/C Heater Control. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

3. CHECK THE (C71) BLOWER MOTOR LOW DRIVER CIRCUIT, THE (C73) BLOWER MOTOR M2 DRIVER CIRCUIT, THE (C72) BLOWER MOTOR M1 DRIVER CIRCUIT, & THE (C70) BLOWER MOTOR HIGH DRIVER CIRCUIT USING A TEST LIGHT




Turn the ignition off.
Disconnect the A/C Heater Control C2 harness connector.
Turn the ignition on.

NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.

Using a 12-volt test light connected to ground, back probe the (C71) Blower Motor Low Driver circuit, the (C73) Blower Motor M2 Driver circuit, the (C72) Blower Motor M1 Driver circuit, and the (C70) Blower Motor High Driver circuit in the A/C Heater Control C2 harness connector.

Q: Does the test light illuminate brightly on each circuit?

YES: Go To 4
NO: Go To 8

4. CHECK THE (C71) BLOWER MOTOR LOW DRIVER CIRCUIT, THE (C73) BLOWER MOTOR M2 DRIVER CIRCUIT, THE (C72) BLOWER MOTOR M1 DRIVER CIRCUIT, & THE (C70) BLOWER MOTOR HIGH DRIVER CIRCUIT FOR A SHORT TO VOLTAGE




Turn the ignition off.
Disconnect the Blower Motor Resistor Block harness connector.
Measure the voltage of the (C71) Blower Motor Low Driver circuit, the (C73) Blower Motor M2 Driver circuit, the (C72) Blower Motor M1 Driver circuit, and the (C70) Blower Motor High Driver circuit in the A/C Heater Control C2 harness connector.

Q: Is there voltage present on any of the circuits?

YES: Repair all circuits with voltage present for a short to voltage. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: GO TO 5

5. CHECK THE (C71) BLOWER MOTOR LOW DRIVER CIRCUIT FOR A SHORT TO THE (C73) BLOWER MOTOR M2 DRIVER CIRCUIT, THE (C72) BLOWER MOTOR M1 DRIVER CIRCUIT, & THE (C70) BLOWER MOTOR HIGH DRIVER CIRCUIT




Measure the resistance between the (C71) Blower Motor Low Driver circuit and the (C73) Blower Motor M2 Driver circuit, the (C72) Blower Motor M1 Driver circuit, and the (C70) Blower Motor High Driver circuit in the A/C Heater Control C2 harness connector.

Q: Is the resistance below 10K ohms between the (C71) Blower Motor Low Driver circuit and any of the other circuits?

YES: Repair all circuits with a resistance below 10k ohms for a short to the (C71) Blower Motor Low Driver circuit. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 6

6. CHECK THE (C73) BLOWER MOTOR M2 DRIVER CIRCUIT FOR A SHORT TO THE (C72) BLOWER MOTOR M1 DRIVER CIRCUIT & THE (C70) BLOWER MOTOR HIGH DRIVER CIRCUIT




Measure the resistance between the (C73) Blower Motor M2 Driver circuit and the (C72) Blower Motor M1 Driver circuit and the (C70) Blower Motor High Driver circuit in the A/C Heater Control C2 harness connector.

Q: Is the resistance below 10K ohms between the (C73) Blower Motor M2 Driver circuit and any of the other circuits?

YES: Repair all circuits with a resistance below 10k ohms for a short to the (C73) Blower Motor M2 Driver circuit. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 7

7. CHECK THE (C72) BLOWER MOTOR M1 DRIVER CIRCUIT FOR A SHORT TO THE (C70) BLOWER MOTOR HIGH DRIVER CIRCUIT




Measure the resistance between the (C72) Blower Motor M1 Driver circuit and the (C70) Blower Motor High Driver circuit in the A/C Heater Control C2 harness connector.

Q: Is the resistance below 10K ohms?

YES: Repair the (C72) Blower Motor M1 Driver circuit for a short to the (C70) Blower Motor High Driver circuit. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the A/C Heater Control. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

8. CHECK THE (C71) BLOWER MOTOR LOW DRIVER CIRCUIT FOR AN OPEN




Turn the ignition off.
Disconnect the Blower Motor Resistor Block harness connector.
Measure the resistance of the (C71) Blower Motor Low Driver circuit between the Blower Motor Resistor Block harness connector and the A/C Heater Control C2 harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Go To 9
NO: Repair the (C71) Blower Motor Low Driver circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

9. CHECK THE (C73) BLOWER MOTOR M2 DRIVER CIRCUIT FOR AN OPEN




Measure the resistance of the (C73) Blower Motor M2 Driver circuit between the Blower Motor Resistor Block harness connector and the A/C Heater Control C2 harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Go To 10
NO: Repair the (C73) Blower Motor M2 Driver circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

10. CHECK THE (C72) BLOWER MOTOR M1 DRIVER CIRCUIT FOR AN OPEN




Measure the resistance of the (C72) Blower Motor M1 Driver circuit between the Blower Motor Resistor Block harness connector and the A/C Heater Control C2 harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Go To 11
NO: Repair the (C72) Blower Motor M1 Driver circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

11. CHECK THE (C70) BLOWER MOTOR HIGH DRIVER CIRCUIT FOR AN OPEN




Measure the resistance of the (C70) Blower Motor High Driver circuit between the Blower Motor Resistor Block harness connector and the A/C Heater Control C2 harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Repair the (C70) Blower Motor High Driver circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the Blower Motor Resistor Block. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
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