Air Conditioning
AIR CONDITIONINGThe climate control system components include the following:
- A/C compressor
- A/C clutch assembly
- A/C condenser core
- A/C evaporator core
- Receiver/drier
- Connecting refrigerant lines
- Thermostatic expansion valve
The refrigerant system incorporates an A/C compressor controlled by the powertrain control module (PCM) through an A/C clutch relay. The climate control assembly sends an A/C request signal to the instrument cluster module which relays the request to the PCM. An evaporator discharge air temperature sensor is used to disengage the A/C compressor clutch when the evaporator core temperature falls below 4°C (39°F).
The A/C compressor clutch will only be engaged by the PCM if all of the following conditions are met:
- The climate control assembly is set to a mode which provides an A/C request to the PCM via the instrument cluster module (ICM).
- The evaporator discharge air temperature sensor is reading a temperature above 4°C (39°F).
- The A/C pressure transducer is not reading a pressure above 2,841 kpa (412 psi) in the high side of the refrigerant system.
- The A/C compressor relay is switched to the CLOSED position by the PCM.
- The engine coolant temperature is not excessively high.
- The PCM has not detected a wide open throttle (WOT) condition.
An A/C pressure relief valve is installed in the A/C manifold and tube to protect the refrigerant system against excessively high refrigerant pressures.
Refrigerant flow into the evaporator core is metered by a thermostatic expansion valve (TXV).
A/C Compressor and Clutch Assembly
NOTE: Internal A/C compressor components are not serviced separately. The variable scroll compressor is serviced only as an assembly. The A/C clutch, A/C clutch pulley and the A/C clutch field coil are serviceable.
The variable scroll A/C compressor has the following characteristics:
- A variable capacity function controlled by a suction pressure sensing device.
- A fixed and orbiting scroll to provide refrigerant compression.
- A non-serviceable shaft seal.
- The A/C compressor uses PAG Refrigerant Compressor Oil YN-12-D WSH-M1C231-B. This oil contains special additives necessary for the A/C compressor.
The A/C compressor contains a thermal cutout switch which senses the compressor housing temperature. The switch will disengage the A/C compressor clutch if the housing temperature exceeds 120°C (247°F).
The magnetic A/C clutch has the following characteristics:
- It drives the compressor shaft.
- When battery positive voltage (B+) is applied to the A/C 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.
- When B+ is removed from the A/C clutch field coil, springs in the clutch disc and hub assembly move the clutch disc away from the A/C clutch pulley.
Condenser Core
NOTE: Installation of a new receiver/drier is not required when repairing the refrigerant system except when there is physical evidence of contamination from a failed A/C compressor or damage to the receiver/drier.
The condenser is an aluminum fin and tube design heat exchanger, located in front of the vehicle radiator. It cools compressed refrigerant gas by allowing air to pass over fins and tubes to extract heat and by condensing gas to liquid refrigerant as it is cooled.
Evaporator Core
NOTE: Installation of a new receiver/drier is not required when repairing the refrigerant system except when there is physical evidence of contamination from a failed A/C compressor or damage to the receiver/drier.
The evaporator core is an aluminum plate/fin type and is located in the heater core and evaporator core housing. A mixture of 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. Air from the blower motor is cooled and dehumidified as it flows through the evaporator core fins.
Thermostatic Expansion Valve
The TXV is located between the evaporator core lines and the thermostatic expansion valve manifold and tube assembly at the 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.
Receiver Drier
NOTE: Installation of a new receiver/drier is not required when repairing the refrigerant system except when there is physical evidence of contamination from a failed A/C compressor or damage to the receiver/drier.
The receiver/drier is mounted to the right of the radiator support. It stores high-pressure liquid after it leaves the condenser core. A desiccant bag mounted inside the receiver/drier removes any retained moisture from the refrigerant.
Evaporator Discharge Air Temperature Sensor
The evaporator discharge air temperature sensor contains a thermistor which receives a reference voltage from the PCM. The thermistor then varies the resistance to the reference voltage based on the evaporator discharge air temperature. The resulting voltage is returned to the PCM where it is interpreted as an evaporator air discharge temperature reading.
The PCM maintains evaporator core temperature and prevents icing of the evaporator core, by disengaging the A/C compressor clutch when the evaporator discharge air temperature sensor reading falls below 4°C (39°F), and by engaging the A/C compressor clutch when the discharge air temperature rises above 5°C (41°F).
The evaporator discharge air temperature sensor is located on the heater core and evaporator core housing in the air-stream leaving the evaporator core.
A/C Pressure Transducer
The A/C pressure transducer monitors the compressor discharge pressure and communicates with the PCM. The PCM will interrupt A/C compressor operation in the event that the A/C pressure transducer indicates high system discharge pressures. It is also used to sense low charge conditions. If the pressure is below a predetermined value for a given ambient temperature, the PCM will not allow the clutch to engage.
Peanut Fitting:
Peanut Fitting
When disconnecting or connecting peanut fittings, observe the following:
- The male and female blocks of the peanut fitting are retained with a nut.
- Support the female fitting with a wrench to prevent twisting of the tubes.
- An O-ring seal is installed around the tube on the male block.
- When correctly assembled, the male and female fittings should be flush.
- Use only the O-ring seal listed in the Ford Master Parts Catalog.
Service Gauge Port Valves
The high-pressure service gauge port valve is located on the compressor manifold and tube assembly near the condenser fitting.
The low-pressure service gauge port valve is located on the evaporator-to-suction accumulator line near the evaporator fitting.
The fitting is an integral part of the refrigeration line or component.
- Special couplings are required for both the high-side and low-side service gauge ports.
- A very small amount of leakage will always be detectable around the Schrader-type valve with the service gauge port valve cap removed, and is considered normal. A new Schrader-type valve core can be installed if the seal leaks excessively.
- The 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.