Chart 3 Improper Blower Speed

CIRCUIT DESCRIPTION

Based on a signal sent from the Body Control Module (BCM), the programmer sends a variable voltage to the power module which is then amplified and sent to the blower motor. The programmer monitors the blower voltage so that the signal can be adjusted to achieve the desired blower motor speed.

TEST DESCRIPTION

Numbers below refer to circled numbers on the diagnostic chart.

1. This step checks for low fan operation.

2. This step checks for high fan operation.

3. This step checks the commanded blower speed input to the programmer.

4. This step checks the commanded blower speed signal out of the BCM.

5. This step checks the blower speed control input to the power module.

6. This step checks the accuracy of variable blower speed control.