Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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 EMTC system:
- The PCM controls the A/C clutch relay.
- The evaporator temperature sensor monitors the temperature of the evaporator core and sends a signal to the PCM. If the temperature of the evaporator core 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.
| Item | Description |
|---|---|
| 1 | High pressure liquid |
| 2 | Low pressure liquid |
| 3 | High pressure vapor |
| 4 | Low pressure vapor |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.