The Refrigerant Cycle

For information regarding base refrigerant operation within the HVAC system, refer to the current Ford Web Based Technical Training courses. The diagram below shows the refrigerant system state in each component on this vehicle.

Some specific items to remember when working with this refrigerant system:

• The PCM controls the A/C clutch relay.
• The evaporator temperature sensor monitors the temperature of the air that has passed through the evaporator core and sends a signal to the PCM. If the temperature of the evaporator core discharge air is low enough to cause the condensed water vapor to freeze, the A/C clutch is disengaged by the PCM.
• The line pressure is monitored so that A/C compressor operation is interrupted if the system pressure becomes too high or too low.
• The A/C compressor relief valve opens and vents refrigerant to relieve unusually high system pressure.

Thermostatic Expansion Valve (TXV) Type Refrigerant System State and Flow 

Courtesy of FORD MOTOR COMPANY