Air Conditioning System: Other Ford Expedition II

Thermostatic Expansion Valve

The thermostatic expansion valve (TXV) is located between the evaporator core lines and the thermostatic expansion valve 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 two separate flow paths. An internal temperature sensing bulb senses the temperature of the refrigerant flowing out of the evaporator core and adjusts an internal pintype 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 Thermostatic Switch

The A/C thermostatic switch monitors the temperature of the refrigerant exiting the evaporator core into the TXV. It is used (by the PCM) to prevent freezing of the evaporator core by controlling A/C compressor clutch engagement/disengagement. Battery voltage is sent to the A/C thermostatic switch (via the low charge protection switch) when the ignition switch is in the RUN position. The A/C thermostatic switch either completes the circuit to the PCM (when the refrigerant temperature rises), or interrupts the circuit (when the refrigerant temperature drops). The PCM engages the A/C compressor clutch when the circuit is complete and an A/C request has been received from the climate control assembly. For specifications regarding operating temperature(s), refer to CLIMATE CONTROL SYSTEM-GENERAL INFORMATION .

The A/C thermostatic switch is mounted on the TXV. Thermal grease must be applied to the A/C thermostatic switch probe when installing it into the TXV.

Low Charge Protection Switch

The low charge protection switch (19E561) is used to prevent A/C compressor damage in the event of a low refrigerant charge, by interrupting voltage to the A/C thermostatic switch and the PCM, when the low side refrigerant pressure drops below acceptable levels. The electrical switch contacts open when the suction pressure drops below normal levels. The contacts close when the suction pressure rises. For specifications regarding operating pressure(s), refer to CLIMATE CONTROL SYSTEM-GENERAL INFORMATION .

The low charge protection switch is mounted on the TXV.

High Pressure Cutoff Switch

The high pressure cutoff switch is used to interrupt A/C compressor operation by interrupting the voltage circuit to the low charge protection switch in the event of high system discharge pressures. When the A/C compressor discharge pressure rises, the switch contacts open to disengage the A/C compressor. When the pressure drops, the contacts close to allow operation of the A/C compressor. For specifications regarding operating pressure(s), refer to CLIMATE CONTROL SYSTEM-GENERAL INFORMATION .

The high pressure cutoff switch is mounted on a Schrader valve-type fitting on the high pressure side of the compressor manifold and tube assembly. It is not necessary to discharge the refrigerant system to remove the high pressure cutoff switch.

Condenser Core

Note. Installation of a new receiver/drier is not required when repairing the air conditioning system except when there is physical evidence of system 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 (8005). 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. If an evaporator core leak is suspected, the evaporator core must be vacuum leak tested before it is removed from the vehicle. For additional information, refer to CLIMATE CONTROL SYSTEM-GENERAL INFORMATION .

Note. Installation of a new receiver/drier is not required when repairing the air conditioning system except when there is physical evidence of system 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 plenum chamber. A mixture of refrigerant and oil enters the bottom of the evaporator core through the evaporator core inlet tube, continues over to the remaining five plate/fin sections, and then moves 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.

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.

A/C Compressor Pressure Relief Valve

An A/C compressor pressure relief valve is incorporated in the compressor manifold and tube assembly to prevent damage to the A/C compressor and other system components, and to avoid total refrigerant loss by relieving unusually high refrigerant system discharge pressure buildups. For additional information, regarding operating pressure(s) specifications, refer to CLIMATE CONTROL SYSTEM-GENERAL INFORMATION .

Scheme 50

Note. Use only the O-ring seals listed in the Ford Master Parts Catalog for the spring lock coupling.

The spring lock coupling is a refrigerant line coupling held together by a garter spring inside a circular cage. When the coupling is connected together, the flared end of the female fitting slips behind the garter spring inside the cage of the male fitting. The garter spring and cage then prevent the flared end of the female fitting from pulling out of the cage. Three O-ring seals are used to seal between the two halves of the couplings. A plastic indicator ring is used on the spring lock couplings of the evaporator core to indicate, during vehicle assembly, that the coupling is connected. Once the coupling is connected, the indicator ring is no longer necessary but will remain captive by the coupling near the cage opening. The indicator ring can also be used during service operations to indicate connection of the coupling. An A/C tube lock coupling clip (19E746) can be used to secure the coupling but is not required.

Peanut Fitting

Some A/C lines use peanut shaped fittings instead of spring lock couplings for attachment and sealing. The male and female blocks of the peanut fitting are retained with a nut. An O-ring seal is installed around the tube on the male block. When correctly assembled the male and female fittings should be flush.

Scheme 51

Service Gauge Port Valves

The high pressure service gauge port valve is located on the compressor manifold and tube assembly.

The low pressure service gauge port valve is located on the thermostatic expansion valve manifold and tube assembly suction tube.

Scheme 52

Note. Always install the A/C charging valve cap (19D702) on the service gauge port valves after repairing the refrigerant system.

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 new Schrader-type valve core can be installed if the seal leaks.

Refer to CLIMATE CONTROL SYSTEM-GENERAL INFORMATION article.

Material

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