Rear A/C Request

When the rear temperature-airflow control is set to full cold, the RHVAC control module activates the rear Thermostatic Expansion Valve (TXV) over a hardwired circuit only if the front A/C system is in operation and the rear evaporator discharge air temperature is above approximately 1 °C (33.8 °F).

The rear evaporator discharge air temperature sensor is a hardwired input to the RHVAC control module. The rear evaporator temperature sensor prevents icing of the rear evaporator core by measuring the temperature of the rear evaporator core. An accurate rear evaporator temperature is critical for rear Thermostatic Expansion Valve (TXV) activation. If the temperature of the rear evaporator is low enough to cause the condensed water vapor to freeze, the rear Thermostatic Expansion Valve (TXV) is deactivated by the RHVAC control module.