Component Description

WARNING: This page is about a different car, the 2015 Lincoln Navigator and 2015 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

A/C Compressor - Fixed Displacement

NOTE: Proper Air Conditioning (A/C) system diagnosis on a vehicle's compressor is dependent on correct refrigerant system charge and tested in ambient temperatures above 21.1°C (70°F).

Fixed displacement A/C compressors are always at 100% displacement. The pistons are placed around an angled plate (swash plate) and are pushed back and forth as the plate rotates. Cooling performance is controlled by switching the compressor clutch on or off depending upon the evaporator temperature.

The fixed displacement compressor has the following characteristics:

A non-serviceable shaft seal.
A serviceable pressure relief valve installed in the rear of the compressor to protect the refrigerant system against excessively high refrigerant pressures.
Uses Motorcraft® 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.

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.

The PCM supplies a 5-volt reference voltage and ground to the A/C pressure transducer. 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 AAT sensor is an input to the PCM. If the outside air temperature is below approximately 0°C (32°F), the PCM does not allow the A/C compressor clutch to engage.

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.

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 blower motor switch position, series resistors are added or bypassed in the blower motor resistor to decrease or increase blower motor speed.

The blower motor has 4 speeds:

for low speed, all 3 resistors are used
for medium-low speed, resistors 1 and 2 are used
for medium-high speed, resistor 1 is used
for high speed, the blower motor is provided a path directly to ground and the blower motor resistors are not used

Compressor Clutch Assembly

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.

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.

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 - Defrost/panel/floor mode

The defrost/panel/floor mode door actuator uses a cam and lever assembly to position the defrost/panel/floor. The defrost/panel/floor mode door actuator contains a reversible electric motor and a potentiometer. The potentiometer allows the HVAC control module to monitor the position of the defrost/panel/floor mode door.

Door Actuator - Temperature

The temperature door actuator contains a reversible electric motor and a potentiometer. The HVAC control module powers the actuator motor to move the temperature door to the desired position. The potentiometer allows the HVAC control module to monitor the position of the temperature door.

On the EMTC system, the temperature door actuator is located on the top of the heater core and evaporator core housing.

Evaporator Core

The evaporator core is an aluminum tube and fin type heat exchanger 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, continues over to the tube and fin sections and then moves out of the evaporator core through the evaporator core outlet tube as a vapor. Airflow from the blower motor is cooled and dehumidified as it flows through the evaporator core fins.

Evaporator Temperature Sensor

The evaporator temperature sensor communicates the evaporator fin temperature to the HVAC control module.

The evaporator temperature information is sent over the CAN to the PCM. The PCM maintains evaporator core temperature and prevents icing of the evaporator core. The icing is prevented by the PCM disengaging the A/C compressor clutch when the evaporator temperature sensor reading falls below approximately 0°C (32°F), and by engaging the A/C compressor clutch when the temperature sensor reading rises above approximately 2°C (35.6°F).

The evaporator temperature sensor electrical connector is located outside of the heater core and evaporator core housing behind the glove compartment. The sensor pigtail leads into the housing to the sensor probe which is inserted between the evaporator core fins.

The evaporator temperature sensor is not available as a separate component. To install a new evaporator temperature sensor, a new heater core and evaporator core housing must be installed. Refer to Climate Control .

Heater Core

The heater core consists of fins and tubes arranged to extract heat from the engine coolant and transfer the heat to air passing through the plenum.

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.

Heating Ventilation Air Conditioning (HVAC) Control Module - Electronic Manual Temperature Control (EMTC)

All customer requests for the EMTC climate control system come through the HVAC control module. The HVAC control module adjusts the climate control system components to achieve the desired selection based on the temperature, air mode and fan speed selection.

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. In MAX A/C mode the recirculated air indicator is illuminated (recirculated air forced on). The recirculated air request button is an integral part of the HVAC control module and cannot be serviced separately.

Receiver Drier

NOTE: Installation of a new receiver drier desiccant bag is not required when repairing the A/C system, except when there is physical evidence of contamination from a failed A/C compressor or damage to the desiccant bag. Damage to the desiccant bag includes physical damage or moisture contamination. Moisture contamination results only from a complete loss of refrigerant, and equalization of the refrigerant system pressure with atmospheric pressure for a period longer than one hour. If even a slight amount of positive refrigerant pressure is present in the refrigerant system before repairs are carried out, the desiccant bag does not need to be replaced.

The receiver drier is integral to the condenser. The receiver drier stores high-pressure liquid. A desiccant bag is used inside the receiver drier to remove excess moisture from the refrigerant. The desiccant bag is a separate component and is removed and installed separately from the condenser.

Refrigerant System Dye

NOTE: Check for leaks using a Rotunda-approved UV lamp and dye enhancing glasses.

A fluorescent refrigerant system dye wafer is added to the receiver drier desiccant bag at the factory to assist in refrigerant system leak diagnosis. 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. Refer to Fluorescent Dye Leak Detection .

Replacement desiccant bags, either separately or part of the receiver drier assembly, are equipped with a new fluorescent dye wafer. It is not necessary to add additional dye to the refrigerant system before diagnosing leaks. If the system has been out of refrigerant through the winter the dye at the leak point may have oxidized and may not fluoresce. If this happens, recharge and operate the A/C system to circulate the oil and allow any residual dye to show up at the leak point. It is important to understand that dye adheres to the oil not the refrigerant; the refrigerant carries the oil out of the leak point.

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 the service gauge port valves to ensure 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. Refer to Electronic Leak Detection .

Courtesy of FORD MOTOR COMPANY

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)

Thermostatic Expansion Valve (TXV)

The TXV is located between the evaporator core lines and the TXV manifold and tube assembly at the RH rear of the engine compartment. The TXV provides a restriction to the flow of refrigerant from the high-pressure side of the refrigerant system, and separates the low-pressure and high-pressure sides of the refrigerant system. Refrigerant entering and exiting the evaporator core passes through the 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.

Control System Inputs - Electronic Manual Temperature Control (EMTC)

HVAC control module

The HVAC control module integrates the temperature control, airflow mode selection, A/C request button, recirculated air request button and rear defog switch into a single unit.

The temperature control setting determines air temperature. Movement of the temperature control from COOL (blue) to WARM (red) causes a corresponding movement of the temperature door and determines the air discharge temperature that the air distribution system maintains. The temperature control switch is an integral part of the HVAC control module and cannot be installed separately.

The airflow mode setting determines discharge air location. Movement of the mode selector causes a corresponding movement of the airflow mode door actuators. The mode selector is an integral part of the HVAC control module and cannot be installed separately.

The A/C request button determines A/C compressor operation, except when the mode selector is in the OFF, MAX or DEFROST mode. The A/C request button is an integral part of the HVAC control module and cannot be installed separately.

The recirculated air request button determines air inlet source, except when the airflow mode selector is in the OFF, MAX or DEFROST mode. The recirculated air request button is an integral part of the HVAC control module and cannot be installed separately.

The rear defog button signals activation of the heated backlight and heated mirrors. The rear defog button is an integral part of the HVAC control module and cannot be installed separately.

The HVAC control module is not equipped with self-test capabilities.

Blower Motor Switch

The blower motor switch controls blower motor speed by adding or bypassing resistors in the blower motor resistor in all function selector positions except OFF. The blower motor switch is mounted to the HVAC control module and can be separately installed.

Control System Outputs - Electronic Manual Temperature Control (EMTC)

Blower Motor Resistor

The blower motor switch varies the blower motor ground circuit resistance by adding or bypassing series resistance in the blower motor resistor. Increased resistance lowers the blower motor speed, and lowered resistance increases blower motor speed. When the blower motor is in the HIGH position, the blower motor resistor is bypassed.

The blower motor resistor is located on the heater core and evaporator core housing near the blower motor.

Temperature Door Actuator

The temperature door actuator moves the temperature door on command from the HVAC control module.

The temperature door actuator contains a reversible electric motor and a potentiometer. The potentiometer circuit consists of a 5-volt reference signal connected to one end of a variable resistor, and a signal ground connected to the other. A signal circuit is connected to a contact wiper, which is driven along the variable resistor by the actuator shaft. The signal to the HVAC control module from the contact wiper indicates the position of the temperature door. The HVAC control module powers the actuator motor to move the temperature door to the desired position. The vehicle occupants use the temperature selector knob to set the desired position.

The temperature door actuator is located on the top of the heater core and evaporator core housing.

Defrost/Panel/Floor Mode Door Actuator

The defrost/panel/floor mode door actuator uses a cam and lever assembly to position the defrost/panel/floor mode doors on command from the HVAC control module. The defrost/panel/floor mode door actuator contains a reversible electric motor and potentiometer. The potentiometer allows the HVAC control module to monitor the position of the defrost/panel/floor mode doors. The potentiometer circuit consists of a 5-volt reference signal connected to one end of a variable resistor, and a signal ground connected to the other. A signal circuit is connected to a contact wiper, which is driven along the variable resistor by the actuator shaft. The signal to the HVAC control module from the contact wiper indicates the position of the defrost/panel/floor mode doors. The HVAC control module powers the actuator motor to move the defrost/panel/floor mode doors to the desired position. The vehicle occupants use the mode selector rotary switch to set the desired position.

Air Inlet Mode Door Actuator

The air inlet mode door actuator contains a reversible electric motor. The HVAC control module powers the actuator motor to the full RECIRC or full FRESH air inlet position, and does not require a potentiometer circuit to monitor its position.

A/C Compressor - Fixed Displacement

NOTE: Proper Air Conditioning (A/C) system diagnosis on a vehicle's compressor is dependent on correct refrigerant system charge and tested in ambient temperatures above 21.1°C (70°F).

The fixed displacement compressor has the following characteristics:

A non-serviceable shaft seal.
A serviceable pressure relief valve installed in the rear of the compressor to protect the refrigerant system against excessively high refrigerant pressures.
Uses Motorcraft® 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.

A/C Pressure Transducer

The PCM supplies a 5-volt reference voltage and ground to the A/C pressure transducer. 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 AAT sensor is an input to the PCM. If the outside air temperature is below approximately 0°C (32°F), the PCM does not allow the A/C compressor clutch to engage.

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.

Blower Motor speed control

The blower motor speed control uses a PWM signal from the HVAC control module to determine the desired blower speed and varies the ground feed for the blower motor to control the speed.

Compressor Clutch Assembly

An A/C clutch diode is integrated into the coil for A/C clutch field coil circuit spike suppression.

Condenser

Door Actuator - Air Inlet

Door Actuator - Defrost/panel/floor mode

Door Actuators - Temperature (Single Zone or Dual Zone)

The temperature door actuators contain a reversible electric motor and a potentiometer. The HVAC control module powers the actuator motor to move the temperature door to the desired position. The potentiometer allows the HVAC control module to monitor the position of the temperature door.

On the EATC system with Single Zone, the temperature door actuator is located on the top of the heater core and evaporator core housing.

On the EATC system with Dual Zone, the driver side temperature door actuator is located on the bottom of the heater core and evaporator core housing. The temperature door-passenger side actuator is located on the top of the heater core and evaporator core housing.

Evaporator Core

Evaporator Temperature Sensor

The evaporator temperature sensor communicates the evaporator fin temperature to the HVAC control module.

Heater Core

The heater core consists of fins and tubes arranged to extract heat from the engine coolant and transfer the heat to air passing through the plenum.

Heater Core and Evaporator Core Housing

Heating Ventilation Air Conditioning (HVAC) Control Module - Electronic Manual Temperature Control (EMTC) Remote Mount

The EATC climate control system is equipped with a remotely mounted HVAC control module that is separate from the control interface. For details on the HVAC control module communication, REFER to Control System Logic . The HVAC control module also controls the outputs for the rear window defrost and heated seats.

The HVAC control module utilizes Field-Effect Transistor (FET) protective circuit strategy for its actuator outputs. Output load (current level) is monitored for excessive current (typically short circuits) and is shut down (turns off the voltage or ground provided by the module) when a fault event is detected. A short circuit DTC is stored at the fault event and a cumulative counter is started.

When the demand for the output is no longer present, the module resets the FET circuit protection to allow the circuit to function. The next time the driver requests a circuit to activate that has been shut down by a previous short (FET protection) and the circuit is still shorted, the FET protection shuts off the circuit again and the cumulative counter advances. When the excessive circuit load occurs often enough, the module shuts down the output until a repair procedure is carried out. The FET protected circuit has 3 predefined levels of short circuit tolerance based on the harmful effect of each circuit fault on the FET and the ability of the FET to withstand it. A module lifetime level of fault events is established based upon the durability of the FET. If the total tolerance level is determined to be 600 fault events, the 3 predefined levels would be 200, 400 and 600 fault events. When each tolerance level is reached, the short circuit DTC that was stored on the first failure cannot be cleared by a command to clear the DTCs. The module does not allow the DTC to be cleared or the circuit to be restored to normal operation until a successful self-test proves that the fault has been repaired. After the self-test has successfully completed (no on-demand DTCs present), DTC U1000:00 and the associated DTC (the DTC related to the shorted circuit) automatically clears and the circuit function returns. When each level is reached, the DTC associated with the short circuit sets along with DTC U1000:00. These DTCs can be cleared using the module self-test, then the Clear DTC operation on the scan tool. The module never resets the fault event counter to zero and continues to advance the fault event counter as short circuit fault events occur. If the number of short circuit fault events reach the third level, then DTCs U1000:00 and U3000:49 set along with the associated short circuit DTC. DTC U3000:49 cannot be cleared and a new module must be installed after the repair. The HVAC control module requires PMI when it is replaced.

In-vehicle temperature and humidity sensor

The in-vehicle temperature and humidity sensor contains a thermistor and a sensing element which separately measures the in-vehicle air temperature and the humidity. The sensor sends those readings to the HVAC control module. The in-vehicle temperature and humidity sensor has an electric fan within the sensor that draws in-vehicle air across the two sensing elements. The HVAC control module may adjust the actuator doors based on the in-vehicle temperature and humidity sensor information to maintain the desired humidity and temperature of the passenger cabin air.

Receiver Drier

Refrigerant System Dye

NOTE: Check for leaks using a Rotunda-approved UV lamp and dye enhancing glasses.

Sunload sensor

The sunload sensor uses two photo diode cells inside of it to measure the intensity of the light that enters into the passenger cabin of the vehicle. Based on this information, the HVAC control module increases blower speed and adjusts the temperature settings to lower the vehicle's interior temperature.

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 the service gauge port valves to ensure 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. Refer to Electronic Leak Detection .

Courtesy of FORD MOTOR COMPANY

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)

Thermostatic Expansion Valve (TXV)

Control System Inputs - Electronic Manual Temperature Control (EMTC)

HVAC control module - Remote Mount

Vehicles equipped with the non touch 4.2 inch display and vehicles equipped with the 8 inch touch screen use a remotely mounted HVAC control module that is separate from the control interface. The FCIM or the FDIM provide the interface for the vehicle occupants to control the climate control system. When selections are made, the FCIM communicates the selections to the HVAC control module through the MS-CAN. The remote HVAC control module controls the climate control system based on the FDIM selections, FCIM selections, or automatically controls the climate control system in the AUTO mode.

The remote mount HVAC control module is located at the top center of the instrument panel and is accessed through the upper instrument panel storage tray opening with the tray removed.

Ambient Air Temperature Sensor

The AAT sensor signal is hard wired to the PCM and is sent over the vehicle communication network. The AAT sensor is located in front of the radiator.

In-Vehicle Temperature and Humidity Sensor

The in-vehicle temperature and humidity sensor contains 2 thermistors, which separately measure the in-vehicle air temperature and humidity and send those readings to the HVAC control module.

Sunload Sensor

The sunload sensor supplies information to the dual-zone HVAC control module indicating sunload. When sunload is detected, the information from the sensor is used to lower the A/C temperature output to compensate for radiant heat warming the vehicle interior and occupants.

Control System Outputs - Electronic Manual Temperature Control (EMTC)

NOTE: Each of the 4 control system outputs may be overridden by the passenger if desired.

When operating in AUTO mode (if equipped), the control system outputs are automatically adjusted by the HVAC control module.

Blower Motor Speed Control

The blower motor speed control controls the blower motor speed by converting low power signals from the HVAC control module to a high current, variable ground feed for the blower motor. A delay function is used to provide a gradual increase or decrease in blower motor speed under all conditions.

The blower motor speed control is located on the heater core and evaporator core housing near the blower motor.

Mode Door Actuators

Two electric mode door actuators are used to position the 3 airflow mode doors on command from the HVAC control module. The 2 mode door actuators each contain a reversible electric motor. The DEFROST/PANEL/FLOOR mode door actuator contains a potentiometer to allow the HVAC control module to monitor the position of the airflow mode doors. The potentiometer circuit consists of a 5-volt reference signal connected to one end of a variable resistor, and a signal ground connected to the other. A signal circuit is connected to a wiper, which is driven along the variable resistor by the actuator shaft. The signal to the HVAC control module from the wiper indicates the position of the airflow mode door. The air inlet mode door actuator is driven to the full RECIRC or full FRESH air inlet position, and does not require a potentiometer circuit to monitor its position.