Automatic

Inspection of HVAC Control Module and its Circuit

HVAC control module and its circuits can be checked at HVAC control module wiring coupler by measuring voltage.

CAUTION: HVAC control module can not be checked by itself. It is strictly prohibited to connect voltmeter to HVAC control module with couplers disconnected from it.

Voltage Check

HVAC Control Module Voltage Table Part 1:

HVAC Control Module Voltage Table Part 2:

HVAC Control Module Voltage Table Part 3:

1. Remove HVAC control module.
2. Check voltage at each terminal as shown.

NOTE: As each terminal voltage is affected by the battery voltage, confirm that it is 11 V or more when ignition switch is ON.

Reference Waveform





NOTE: The shape of waveform varies with engine coolant temperature.




Waveform at 0 °C (32 °F)




Waveform at 40 °C (104 °F)




Waveform at 80 °C (176 °F)