Chart 1 No Blower Operation/Improper Blower Speed

CIRCUIT DESCRIPTION
The airflow is controlled by modulating the commanded blower voltage which varies the blower speed. The blower is a function of the program number when it is under automatic control with adjustments being made based on vehicle speed, coolant temperature, and Sun Load Sensor load. There are special cases which may override the normal operation of the blower such as to limit snow ingestion, purge air ducts, cooling the instrument panel cluster, or enhance heater warm-up performance.

TEST DESCRIPTION
If the blower is inoperative in normal operating procedures, but operates properly in override, the Instrument Panel Cluster (IPC) or data line between the IPC and Air Conditioning Programmer (ACM) would be suspect.
1. Checks the blower control output to determine if the ACM is sending voltage to the blower or if problem could be in the circuitry.
2. Checks the ACM to determine if output is correct and looks at the input to the blower motor to check for opens in the circuit. If input and output are similar, it indicates a problem with the speed control within the blower assembly.
3. Since the automatic control operation of the blower undergoes adjustments based on vehicle speed, coolant temperature, and Sun Load Sensor load, a properly operating blower may be controlled improperly.