Blower Motor Inoperative at Any Speed Front
Circuit Description
The airflow is controlled by modulating the commanded blower voltage that varies the blower speed. Under automatic control, the blower adjustments are made based upon the following factors:
| • | The vehicle speed |
| • | The coolant temperature |
| • | The sun load sensor |
Special cases exist that may override the normal operation of the blower in order to limit the following conditions:
| • | Snow ingestion |
| • | Purging the air ducts |
| • | Cooling the instrument panel cluster |
| • | Enhancing the heater warm-up performance |
Test Description
If the blower is inoperative in the normal operating procedure, but operates properly in override, the IPC or the data line between the IPC and the heater and A/C programmer are suspect.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
2 |
Did you complete the procedure? | -- | Go to Step 3 | -- |
3 | Is the blower non-operational or intermittent? | -- | Go to Step 6 | Go to Step 4 |
4 | Does the blower speed consistently decrease at a gradual rate from 99 to approximately 30, and then stop? | -- | Go to Step 7 | Go to Step 5 |
5 | Is the blower speed consistent, then OFF? | -- | Go to Step 8 | -- |
6 |
Does the commanded value equal the displayed value on the Scan Tool ? | -- | Go to Step 10 | Go to Step 9 |
7 | The blower is operating properly. Inspect for improper temperature control. Did you inspect for improper temperature control? | -- | Go to Step 18 | -- |
8 |
Is the voltage greater than the specified value? | 9 V | Go to Step 17 | Go to Step 13 |
9 |
Is the blower speed (%) within the specified value? | 40-100 % | Go to Step 10 | Go to Step 11 |
10 | Measure the voltage at the blower motor connector B. Is the voltage less than the specified value? | 4 V | Go to Step 13 | Go to Step 12 |
11 | Replace the heater and A/C programmer. Refer to Programmer Replacement . Is the repair complete? | -- | Go to Step 18 | -- |
12 |
Is the resistance greater than the specified value? | 1.0 ohms | Go to Step 14 | Go to Step 15 |
13 |
Did you complete the repair? | -- | Go to Step 18 | -- |
14 |
Did you complete the repair? | -- | Go to Step 18 | -- |
15 |
Is the resistance less than the specified value? | 50 ohms | Go to Step 19 | Go to Step 20 |
16 | Replace the blower motor assembly. Refer to Blower Motor and Fan Replacement . Did you complete the repair? | -- | Go to Step 18 | -- |
17 | Set the blower speed to HI. Does the voltage change to less than the specified value? | 4 V | Go to Step 16 | Go to Step 13 |
18 |
Did you clear the DTCs and verify the operation? | -- | Go to Diagnostic System Check | -- |
19 | Inspect CKT 50 for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Diagnostic System Check | -- |
20 |
Is the resistance less than the specified value? | 250K ohms | Go to Step 13 | Go to Step 16 |
Blower Motor Inoperative at Any Speed Rear
Circuit Description
Power is available from the CONSOLE fuse through the switch to the blower motor and ground. A series of 3 resistors contained in a module vary the circuit amperage that controls the blower speed. The heater and A/C programmer receives a feedback voltage signal, but this has no effect on the rear blower operation.
Test Description
The numbers below refer to step numbers on the diagnostic table.
-
If CKT 52, CKT 850, and the HI position have continuity, the measurement will be near zero. As slower speeds are selected, the ground path of the blower motor passes through more resistors in the module. More resistors in the ground path increases the voltage at S345. Turn off the rear blower switch in order to measure the voltage.
-
If a resistor in the module is open, all of the cavities beyond that resistor will also be open. If cavity E operates the blower, then the fault is in the switch or in the wiring to the switch.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Functional Check? | -- | Go to Step 2 | Go to Functional Check | ||||||||
2 |
Does the rear blower motor operate in any setting? | -- | Go to Step 6 | Go to Step 3 | ||||||||
3 |
Does the voltage measure near the specified value? | B+ | Go to Step 4 | Go to Step 7 | ||||||||
4 |
Does the resistance measure within the specified range? | 0-1 ohms | Go to Step 5 | Go to Step 12 | ||||||||
5 | Connect a test light across the harness terminals A and B. Refer to Troubleshooting with a Test Lamp in Wiring Systems. Did the test light illuminate? | -- | Go to Step 10 | Go to Step 13 | ||||||||
6 |
Refer to Using Fused Jumper Wires in Wiring Syetems. Does the blower motor run at the correct speeds? | -- | Go Step 8 | Go to Step 9 | ||||||||
7 |
Did you find and correct the condition? | 0-6 amperes | Go to Functional Check | Go to Step 11 | ||||||||
8 | Inspect for faulty connections/terminal tension at the rear blower motor switch connector. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Functional Check | Go to Step 16 | ||||||||
9 |
Did you find and repair the condition? | -- | Go to Functional Check | Go to Step 15 | ||||||||
10 |
Did the test light illuminate? | -- | Go to Functional Check | Go to Step 14 | ||||||||
11 |
Did you find and repair the condition? | -- | Go to Functional Check | -- | ||||||||
12 |
Did you find and repair the condition? | -- | Go to Functional Check | -- | ||||||||
13 |
Did you find and repair the condition? | -- | Go to Functional Check | -- | ||||||||
14 |
Did you find and repair the condition? | -- | Go to Functional Check | -- | ||||||||
15 | Replace the resistor module. Did you complete the repair? | -- | Go to Functional Check | -- | ||||||||
16 | Replace the rear blower motor switch. Did you complete the repair? | -- | Go to Functional Check | -- |
