Temperature Valve Actuators

When the HVAC system is in the OFF mode, pressing any HVAC switch will actuate the automatic HVAC system. If the heater and A/C control displays any temperature between 19°-29°C (66°-84°F), turning the temperature switch will increase/decrease the set temperature by 1 degree. If the temperature is setting is 30°C (85°F), turning the temperature switch up increases the set temperature to 32°C (90°F).

The left hand temperature valve actuator is a DC stepper motor by design. The stepper motor has four field windings that are controlled by the heater and A/C control. When the heater and A/C control needs to move the stepper motor, it energizes the proper field windings which rotates the armature a fixed amount in the proper direction. This fixed amount is called a step. Battery voltage for the stepper motor is supplied by the heater and A/C control when the ignition is in the ON position, through the battery positive power supply circuit. Attached to the stepper motor is a small gear. When the stepper motor is installed on the HVAC module, it meshes with a larger gear which is part of an assembly that drives the linkage of the air mix door. The motor opens the air mixture door to a position to divert sufficient air past the heater core to achieve the desired vehicle temperature.

The right hand temperature valve actuator is a DC stepper motor by design. The stepper motor has four field windings that are controlled by the heater and A/C control. When the heater and A/C control needs to move the stepper motor, it energizes the proper field windings which rotates the armature a fixed amount in the proper direction. This fixed amount is called a step. Battery voltage for the stepper motor is supplied by the heater and A/C control when the ignition is in the ON position, through the battery positive power supply circuit.

Attached to the stepper motor is a small gear. When the stepper motor is installed on the HVAC module, it meshes with a larger gear which is part of an assembly that drives the linkage of the air mix door. The motor opens the air mixture door to a position to divert sufficient air past the heater core to achieve the desired vehicle temperature.