Chart 2 No Blower Operation/Improper Blower Speed

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The air flow 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 solar load. There are special cases which may override the normal operation of the blower such as to limit snow ingestion, purge air ducts, cool the instrument panel cluster, or enhance heater warm-up performance.

TEST DESCRIPTION

Using on-board diagnostics allows us to override the climate control panel request. 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 (ACP)Air Conditioning Programmer (ACP) would be suspect.

1. This branch looks at the blower control output to determine if the ACP is sending voltage to the blower or if problem could be in the circuitry.

2. This branch looks at the programmer 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 solar load, a properly operating blower may be controlling improperly. chart 4 includes sensor tests which may identify a problem with the sensor inputs.

4. This vehicle uses an IPC cooling mode to protect the IPC electronics from overheating under high in-car temperature conditions. If the temperature inside the vehicle exceeds 125°F even if "OFF" has been selected, the blower will be enabled and will run until in-car temperature drops below 121°F.

NOTES ON INTERMITTENT CONNECTION
If an intermittent DTC is being set, select Air Conditioning Programmer (ACP) Snapshot Data for DTC and note value of ACP data parameter. Manipulate the related wiring while observing ACP data parameter. If a failure is induced, the displayed data parameter value will be outside the sensors normal operating range.