The Refrigerant Cycle

For base operation regarding refrigerant operation within the HVAC system, please reference the current Ford Web Based Technical Training courses. The diagram below shows the states of the refrigerant in each component of the system for this vehicle. Please reference the diagram along with the training information for an understanding of the refrigerant cycle within this vehicle.

Some specific items to remember when working with this 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

Control System Logic 

The blower motor knob must be set to any speed other than 0 for the system to operate.