Air Conditioning: Other Jaguar S-type I рестайлинг

A/C Compressor Pressure Relief Valve

An A/C compressor pressure relief valve is incorporated in the compressor A/C manifold and tube to

1. relieve unusually high refrigerant system discharge pressure buildups.
2. prevent damage to the A/C compressor and other system components.
3. avoid total refrigerant loss by closing after the excessive pressure has been relieved.

Scheme 42

The A/C condenser core has the following characteristics

1. It is an aluminum fin and tube design heat exchanger located in front of the vehicle radiator.
2. 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.

1. The tube assembly mounted on the side of the condenser core contains the desiccant bag.

Desiccant bag

The desiccant bag removes any retained moisture in the A/C system. The A/C system has an R-134a leak trace dye wafer incorporated into the desiccant bag.

Refrigerant Lines

The manifold and tube assembly - thermostatic expansion valve carries high pressure liquid to the thermostatic expansion valve and low pressure gas from the thermostatic expansion valve to the manifold and tube assembly-compressor.

The manifold and tube assembly - A/C compressor carries the high pressure gas from the A/C compressor to the condenser core. It also carries the low pressure gas received from the manifold and tube assembly-thermostatic expansion valve to the compressor, houses the low pressure service port and has a serviceable high pressure relief valve.

1. The manifold and tube assembly - A/C compressor used vehicles with fitted 4.2L engine are not interchangeable With vehicles fitted with 2.5L and 3.0L engine.

The tube assembly - condenser to thermostatic expansion valve carries high pressure liquid to the manifold and tube assembly-thermostatic expansion and houses the high pressure service port.

Evaporator Core

The A/C evaporator core is the plate/fin type with a unique refrigerant flow path.

1. A mixture of refrigerant and oil exits the thermostatic expansion valve (TXV) and enters the evaporator tank area through the 12.7 mm (0.5 in) tube.
2. The tank area is divided into three sections: front inlet, front outlet and rear tank.
3. The refrigerant enters the evaporator core tank area at the front inlet, flows down through the core and up the back side in a "U-flow" pattern.
4. The refrigerant moves into the rear tank area and across to the other half of the core. The refrigerant moves down through the core and back up the front side of the core to the front outlet tank area.
5. The refrigerant at this point is in a gaseous state. It exits the evaporator through the 16 mm (0.64 in) tube then passes through the TXV.

Scheme 43

The thermostatic expansion valve has the following characteristics

1. It is mounted on the evaporator core supply and return lines.
2. It is a block-type valve.
3. It contains an internal sensing bulb to increase the effectiveness of temperature sensing.
4. It is not serviceable. A new thermostatic expansion valve must be installed as a unit.

Pressure cutoff switch

The pressure cutoff switch monitors the A/C compressor discharge pressure and communicates with the ECM. The ECM will interrupt A/C compressor operation in the event that the pressure cutoff switch indicates high system discharge pressures. It is also used to sense no or low charge conditions. If the pressure is below a predetermined value for a given ambient temperature, the ECM will not allow the clutch to engage.

1. The pressure cutoff switch is mounted on a Schrader-type valve fitting on the compressor to condenser discharge line.
2. A valve depressor, located inside the threaded end of the pressure cutoff switch, presses on the Schrader valve stem and allows the pressure cutoff switch to monitor the compressor discharge pressure.
3. When the compressor discharge pressure rises to approximately 2,896 kPa (420 psi), the ECM will interrupt the compressor clutch coil circuit and disengage the compressor.
4. When the pressure drops to approximately 1,724 kPa (250 psi) the ECM will enable the A/C compressor circuit.
5. Controls the signal to the ECM to control the fan speed.

Service Gauge Port Valves

The high-pressure service gauge port valve is located on the tube assembly - condenser to thermostatic expansion valve.

The low pressure service gauge port valve is located on the manifold and tube assembly - A/C compressor.

Scheme 44

The fitting is an integral part of the refrigerant line or component.

1. Special couplings are necessary for both the high side and low side service gauge ports.
2. A new Schrader-type valve can be installed if the seal leaks
3. Always install the A/C charging valve cap on the service gauge port valves after repairing the refrigerant system.

For additional information refer to Climate Control System - General Information article.

Scheme 45

Scheme 46

1. Carry out the air conditioning (A/C) system recovery procedure. Refer to «Air Conditioning (A/C) System Recovery, Evacuation and Charging»(ref-311264-S30880593692009032500000) article.
2. Disconnect the battery ground cable. Refer to «Battery Disconnect»(ref-311319-S30990335982009032500000) article.
3. Remove the air deflector. Refer to «Air Deflector»(ref-311270-S01637873752009032500000) article.
4. Detach the accessory drive belt. Rotate the accessory drive belt tensioner counter-clockwise. Use a 3/8 inch square drive bar to rotate the accessory drive belt tensioner. Detach the accessory drive belt.
5. Disconnect the A/C compressor supply and return lines. Remove and discard the A/C compressor O-ring seals. Cap the exposed ports.
6. Disconnect the A/C compressor electrical connector.
7. Remove the A/C compressor.