Dual Zone Control Switch

Passenger temperatures can be set anywhere between 16°C (60°F) to 32°C (90°F). To activate the dual zone, the passenger presses the right air temperature switch, then turns it to the desired temperature offset. The passenger side temperature will appear on the VF display to show the desired temperature. There are two temperature doors, driver (LH) and passenger (RH). Each temperature door is controlled by a corresponding temperature valve actuator, LH or RH respectively. The temperature valve actuators move the associated temperature door to the desired positions which in turn produce the proper temperature of the air delivered to each side of the passenger compartment. The actuators are controlled by the temperature control knobs on the heater and A/C control. The LH temperature control knob is the primary control for both of the actuators. When the MODE button on the heater and A/C control is depressed, the LH temperature control knob will operate both of the actuators to obtain the same temperature to both the LH and RH sides of the passenger compartment. When the AUTO button is depressed, the RH temperature control knob will control the RH actuator to provide a different temperature to the RH side of the passenger compartment, unless the LH temperature control knob is set to the maximum cold or the maximum hot setting. If the LH temperature control knob is set to the maximum cold or the maximum hot setting, the LH temperature control knob will control both the LH and RH actuators. When the LH temperature control knob is in any other position, the RH temperature control knob may be used to control the RH actuator. When the LH temperature control knob is in the full cold position, the actuators position the temperature valves such that the air flow will by-pass the heater core.

With the knob in any other position but full cold, the actuators position the temperature valves to allow air to pass through the heater core. The hotter the control knob setting, the more air passes through the heater core, increasing the air temperature entering the passenger compartment.

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.