The Refrigerant Cycle

For information regarding basic HVAC system refrigerant operation, refer to the current Ford Web Based Technical Training courses. The following diagram shows the refrigerant system state in each component.

The following are characteristics of the DATC system:

• When conditions are correct, the PCM sends a request to the ACCM to engage the electric A/C compressor.
• A thermistor monitors the temperature of the air that has passed through the evaporator and controls electric A/C compressor speed. If the temperature of the evaporator discharge air is low enough to cause the condensed water vapor to freeze, the electric A/C compressor reduces its speed.
• The high-side line pressure is also monitored so that electric A/C compressor operation will be interrupted if the system pressure becomes too high.
• The low-side line pressure is also monitored so that electric A/C compressor operation will be interrupted if the system pressure is determined to be too low (low charge condition).
• The electric A/C compressor thermal protection switch will interrupt compressor operation if the compressor housing exceeds temperature limits.
• The A/C compressor relief valve opens and vents refrigerant to relieve unusually high system pressure.

Courtesy of FORD MOTOR COMPANY