Component Description
Electric Booster Heater
For system operation and component description information on the electric booster heater, REFER to: Supplemental Climate Control - System Operation and Component Description
Rear Climate Control
For system operation and component description information on the rear climate control system, REFER to: Rear Climate Control - System Operation and Component Description
HVAC Control Module
The blower motor speed switch is mounted in the HVAC control module and controls blower motor speed by adding or bypassing resistors in the blower motor resistor in all modes except OFF. The blower motor speed switch is serviced only as an assembly with the HVAC control module.
The temperature control switch adjusts the discharge air temperature. Movement of the temperature knob from cool to warm causes A/Corresponding movement of the temperature door. The position of the temperature door determines the discharge air temperature. The temperature control selector is an integral part of the HVAC control module and cannot be serviced separately.
The airflow mode setting adjusts the discharge air outlet location. Each airflow mode selector icon causes A/Corresponding movement of the airflow mode doors and determines the discharge air outlet location. The airflow mode selector knob is an integral part of the HVAC control module and cannot be serviced separately.
The A/C button determines A/C compressor operation, except when the temperature selector is set to MAX A/C or the airflow mode selector is in defrost mode. The A/C button is an integral part of the HVAC control module and cannot be serviced separately.
The recirculated air request button can be activated in any mode except defrost, and in any mode except MAX A/C. The recirculated air request button is an integral part of the HVAC control module and cannot be serviced separately.
Blower Motor
The blower motor pulls air from the air inlet and forces it into the heater core and evaporator core housing and the plenum chamber where it is mixed and distributed. All airflow from the blower motor passes through the evaporator core.
Blower Motor Resistor
The blower motor resistor uses 3 resistance elements mounted on a resistor board to provide 4 blower motor speeds. Depending on the heater blower motor switch position, series resistors are added or bypassed in the blower motor resistor to decrease or increase blower motor speed.
Evaporator Core
The evaporator core is an aluminum tube and fin type and is located in the heater core and evaporator core housing. A mixture of liquid refrigerant and oil enters the bottom of the evaporator core through the evaporator core inlet tube and continues out of the evaporator core through the evaporator core outlet tube as a vapor. During A/C compressor operation, airflow from the blower motor is cooled and dehumidified as it flows through the evaporator core fins.
Heater Core
The heater core consists of fins and tubes arranged to extract heat from the engine coolant and transfer it to air passing through the heater core.
Heater Core and Evaporator Core Housing
The heater core and evaporator core housing directs airflow from the blower motor through the evaporator core and heater core. All airflow from the blower motor passes through the evaporator core. The airflow is then directed through or around the heater core by the temperature door. After passing through the heater core, the airflow is distributed to the selected outlet by the airflow mode doors.
Door Actuator - Air Distribution
The air distribution door actuator is a stepper motor style actuator. The HVAC control module monitors the air distribution door position by counting the motor steps as it rotates. The HVAC control module drives the actuator motor in the direction necessary to move the air distribution doors to the position set by the air distribution control selection knob.
Door Actuator - Air Inlet
The air inlet door actuator moves the air inlet door between the fresh and recirculated air positions on command from the HVAC control module. The air inlet door actuator is driven to, and automatically stops at, the full recirculated air or full fresh air inlet position and does not require a potentiometer circuit to monitor its position. The air inlet door does not stop at any point between the recirculated air or fresh air inlet position.
Door Actuator - Temperature
The temperature door actuator is a stepper motor style actuator. The HVAC control module monitors the temperature door position by counting the motor steps as it rotates. The HVAC control module drives the temperature door actuator motor in the direction necessary to move the temperature door to the position set by the temperature selection knob.
A/C Pressure Transducer
The PCM monitors the discharge pressure measured by the A/C pressure transducer. As the refrigerant pressure changes, the resistance of the A/C pressure transducer changes. It is not necessary to recover the refrigerant before removing the A/C pressure transducer.
A 5-volt reference voltage is supplied to the A/C pressure transducer from the PCM. The A/C pressure transducer receives a ground from the PCM. The A/C pressure transducer then sends a voltage to the PCM to indicate the A/C refrigerant pressure.
Ambient Air Temperature (AAT) Sensor
The Ambient Air Temperature (AAT) sensor is an input to the PCM. If the temperature is below approximately 0°C (32°F), the PCM does not allow the A/C compressor clutch to engage.
Evaporator Temperature Sensor
The evaporator temperature sensor contains a thermistor. Sensor resistance varies with evaporator temperature. As the temperature rises, the resistance falls. As the temperature falls, the resistance rises. The evaporator temperature sensor is an input to the BCM and the information is relayed to the PCM over the HS-CAN. If the temperature is below approximately 1°C (33.8°F), the PCM does not allow the A/C compressor clutch to engage.
A/C Compressor Clutch
When battery voltage is applied to the A/C compressor clutch field coil, the clutch disc and hub assembly is drawn toward the A/C clutch pulley. The magnetic force locks the clutch disc and hub assembly and the A/C clutch pulley together as one unit, causing the compressor shaft to rotate with the engine. When battery voltage is removed from the A/C compressor clutch field coil, springs in the clutch disc and hub assembly move the clutch disc away from the A/C clutch pulley.
An A/C clutch diode is integrated into the coil for A/C clutch field coil circuit spike suppression.
Internally Controlled Variable Displacement Compressor (2.5L engine)
Variable displacement compressor internals are similar to fixed displacement compressors. The pistons are placed around an angled plate (swash plate) and are pushed back and forth as the plate rotates. Variable displacement compressors vary the swash plate angle to allow piston displacement to vary from 5% (default) to 100% of full capacity to meet cooling demand.
The internally controlled variable displacement compressor has the following characteristics:
- A non-serviceable shaft seal.
- A non-serviceable pressure relief valve installed in the rear of the compressor to protect the refrigerant system against excessively high refrigerant pressures.
- Uses Motorcraft® Polyalkylene Glycol (PAG) Refrigerant Compressor Oil YN-12-D. This oil contains special additives required for the A/C compressor. The oil may have some slightly dark-colored streaks while maintaining normal oil viscosity. This is normal for this A/C compressor because of break-in wear that can discolor the oil.
The piston displacement of the internally controlled variable displacement compressor is controlled with a bellows actuated control valve located in the compressor rear head. The control valve senses the refrigerant suction and head pressures and regulates the pressure in the crankcase. Swash plate angle is a result of the balance of the crankcase pressure on one side of the pistons and suction and head pressure on the other side. The suction pressure varies with the evaporator core temperature. The valve regulates the amount of refrigerant being discharged by an optimum compressor displacement, resulting in the requested evaporator core temperature of approximately 3°C (37.4°F).
Externally Controlled Variable Displacement Compressor (1.6L engine)
Variable displacement compressor internals are similar to fixed displacement compressors. The pistons are placed around an angled plate (swash plate) and are pushed back and forth as the plate rotates. Variable displacement compressors vary the swash plate angle to allow piston displacement to vary from 5% (default) to 100% of full capacity to meet cooling demand.
The externally controlled variable displacement compressor has the following characteristics:
- A non-serviceable shaft seal.
- A non-serviceable pressure relief valve installed in the rear of the compressor to protect the refrigerant system against excessively high refrigerant pressures.
- Uses Motorcraft® Polyalkylene Glycol (PAG) Refrigerant Compressor Oil YN-12-D. This oil contains special additives required for the A/C compressor. The oil may have some slightly dark-colored streaks while maintaining normal oil viscosity. This is normal for this A/C compressor because of break-in wear that can discolor the oil.
The piston displacement of the externally controlled variable displacement compressor is controlled by a PWM signal from the PCM which electronically drives the control valve. The control valve drives the crankcase pressure and thus the swash plate angle. The externally controlled variable displacement compressor achieves precise cooling capability based on the cabin temperature and driving conditions, resulting in the target evaporator core temperature. The target evaporator core temperature range for the EATC system is 3-8°C (37.4-46.4°F); 3-5°C (37.4-41°F) for the EMTC system.
The PCM pulse width modulates the ground to the externally controlled variable displacement compressor solenoid to change the A/C compressor displacement by changing the swash plate angle based on the following items:
- ambient air temperature
- engine revolutions per minute
- evaporator temperature
- High side and low side A/C pressures
- Temperature and mode settings of the climate control head
Thermostatic Expansion Valve (TXV)
The Thermostatic Expansion Valve (TXV) is located at the evaporator core inlet and outlet tubes at the center rear of the engine compartment. The Thermostatic Expansion Valve (TXV) provides a restriction to the flow of refrigerant and separates the low-pressure and high-pressure sides of the refrigerant system. Refrigerant entering and exiting the evaporator core passes through the Thermostatic Expansion Valve (TXV) through 2 separate flow paths. An internal temperature sensing bulb senses the temperature of the refrigerant flowing out of the evaporator core and adjusts an internal pin-type valve to meter the refrigerant flow into the evaporator core. The internal pin-type valve decreases the amount of refrigerant entering the evaporator core at lower temperatures and increases the amount of refrigerant entering the evaporator core at higher temperatures.
A/C Condenser
The A/C condenser is an aluminum tube and fin design heat exchanger. It cools compressed refrigerant gas by allowing air to pass over fins and tubes to extract heat, and condenses gas to liquid refrigerant as it is cooled.
Receiver-Drier
The receiver-drier stores high-pressure liquid and the desiccant bag mounted inside the receiver-drier removes any retained moisture from the refrigerant.
For 1.6L EcoBoost and 2.5L Duratec engine equipped vehicles, the receiver-drier is incorporated into the LH side of the A/C condenser. The receiver-drier element is a separate component and can be removed and installed with the A/C condenser in the vehicle.
Service Gauge Port Valves
The service gauge port valve is an integral part of the refrigerant line or component.
- Prior to leak testing, blow air over service gauge port valves to insure an accurate test.
- Special couplings are required for both the high-side and low-side service gauge ports.
- A very small amount of leakage around the Schrader-type valve with the service gauge port valve cap removed is considered normal. Install a new Schrader-type valve core if the seal leaks excessively.
- The A/C service gauge port valve caps are used as primary seals in the refrigerant system to prevent leakage through the Schrader-type valves from reaching the atmosphere. Always install and tighten the A/C service gauge port valve caps to the correct torque after they are removed.
- Follow the procedure and the notes for electronic leak testing to: Electronic Leak Detection
| Item | Description | Torque |
|---|---|---|
| 1 | Low-pressure service gauge port valve cap | 0.8 Nm (7 lb-in) |
| 2 | Low-pressure service gauge port valve | - |
| 3 | Low-pressure Schrader-type valve | 2.26 Nm (20 lb-in) |
| 4 | High-pressure Schrader-type valve | 3.4 Nm (30 lb-in) |
| 5 | High-pressure service gauge port valve | - |
| 6 | High-pressure service gauge port valve cap | 0.8 Nm (7 lb-in) |
Refrigerant System Dye
A fluorescent refrigerant system dye wafer is added to the receiver-drier desiccant bag at the factory to assist in refrigerant system leak diagnosis using a Rotunda-approved UV blacklight. This fluorescent dye wafer dissolves after about 30 minutes of continuous A/C operation. It is not necessary to add additional dye to the refrigerant system before diagnosing leaks, even if a significant amount of refrigerant has been removed from the system.