Air Temperature Actuators

When the HVAC system is in the OFF mode, pressing any HVAC switch will actuate the automatic HVAC system. If the HVAC control module 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 air temperature actuator is an electronic stepper motor with feedback potentiometers. Zero volts drives the actuator in one direction while S volts moves the actuator in the opposite direction. When the actuator receives 2.5 volts, actuator rotation stops. When a desired temperature is requested, a signal is sent from the HVAC control module to the left air temperature actuator on the air temperature door control circuit. A 5-volt reference signal is sent out over the 5-volt reference circuit, from the HVAC control module, to the left air temperature actuator. When a desired temperature setting is selected, whether manual or automatic, the logic circuit is used to determine the left air temperature door position sensor signals value. A separate 5-volt reference is sent from the HVAC control module to the logic circuit. The HVAC control module software uses this reference voltage to determine the left air temperature actuator position through the air temperature door position signal circuit. 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 air temperature actuator operates the same as the left side. The right air temperature actuator is an electronic stepper motor with feedback potentiometers. Zero volts drives the actuator in one direction while 5 volts moves the actuator in the opposite direction. When the actuator receives 2.5 volts, actuator rotation stops. When a desired temperature is requested, a signal is sent from the HVAC control module to the right air temperature actuator on the auxiliary air temperature door control circuit. A 5-volt reference signal is sent out over the 5-volt reference circuit, from the HVAC control module, to the right air temperature actuator. When a desired temperature setting is selected, whether manual or automatic, the logic circuit is used to determine the right air temperature door position sensor signals value. A separate 5-volt reference is sent from the HVAC control module to the logic circuit. The HVAC control module software uses this reference voltage to determine the right air temperature actuator position through the auxiliary air temperature door position signal circuit. The motor opens the air mixture door to a position to divert sufficient air past the heater core or evaporator to achieve the desired vehicle temperature.