Air Temperature Actuator

The air temperature actuator is a 3-wire bi-directional electric motor. Ignition 3 voltage, ground and control circuit enable the actuator to operate. The control circuit uses a zero to 12 volt linear-ramped signal to command the actuator movement. The zero and 12 volt control values represent the opposite limits of the actuator range of motion. The values in between zero to 12 volts correspond to the positions between the limits.

When the HVAC control module sets a commanded, or targeted, value, the control signal is set to a value between zero to 12 volts. The actuator shaft rotates until the commanded position is reached. The module will maintain the control value until a new commanded value is needed. When full cold is selected, a low voltage, near ground, is applied to control circuit. When full hot is selected, a high voltage, 12 volts, is applied to the control circuit.