| Description and Operation The air conditioning system is controlled by an thermostatic expansion valve. R134a refrigerant is used. Two options are available: - manual climate control
- Air conditioning system with automatic temperature control (DEATC)
Depending on the engine variant, two different air conditioning compressors are used: - Visteon VS16 compressor with variable stroke for 1.6L Duratec-16V Ti-VCT (Sigma), 2.0L Duratec-HE (MI4), 2.3L Duratec-HE (MI4), 1.8L Duratorq-TDCi (Lynx), 2.0L Duratorq-TDCi (DW) engines
- Zexel KC88 compressor with variable stroke and electronically regulated control valve for 2.5L Duratec-ST (VI5) engines
In order to prevent icing of the evaporator, the vehicles are equipped with a temperature sensor on the evaporator. The sensor measures the surface temperature of the cooling fins on the evaporator. If the measured temperature drops below a temperature of approx. +2 °C then the compressor clutch is deactivated. If the temperature increases above +4 °C the compressor is switched back on again. On systems with manual temperature control, the sensor signal is sent via the generic electronic module (GEM) and the CAN bus to the powertrain control module (PCM), which then switches the compressor clutch on and off. On systems with automatic temperature control (DEATC) the sensor signal is first sent to the air conditioning module and then via the CAN bus to the PCM, which then switches the compressor clutch on and off. Refrigerant circuit | Item | Description | | 1 | Condenser | | 2 | A/C compressor | | 3 | Blower motor | | 4 | Evaporator | | 5 | Expansion valve | | 6 | Refrigerant drier | | 7 | Cooling fan | | 8 | High pressure (gaseous and hot) | | 9 | High - pressure (liquid and warm) | | 10 | Low - pressure (liquid and cool) | | 11 | Low-pressure (gaseous and cool) | Function The refrigerant compressor (2) which is driven by the engine sucks in the gaseous refrigerant from the evaporator (5) and compresses it. The temperature of the refrigerant rises to a value between 70 °C and 110 °C. It passes to the condenser (1) under high pressure. At this point heat is drawn from the refrigerant by the air being forced past the cooling fins. Because of this heat loss, the refrigerant liquefies and leaves the condenser. The refrigerant then passes under high pressure to the refrigerant drier (8). This serves as a storage medium and filters out any moisture contained in the refrigerant. The expansion valve (6) regulates the quantity of refrigerant injected into the evaporator (5) as a function of the pressure and temperature in the evaporator. The liquid refrigerant is vaporized in the evaporator. This causes heat to be extracted from the air coming into the vehicle. The air therefore cools down and the moisture it contained is given up at the evaporator core. The gaseous flow of refrigerant which comes out from the evaporator at low pressure enters the expansion valve at the upper opening, from where it is sucked in by the refrigerant compressor. The A/C pressure converter sensor sends an analog signal to the PCM. After evaluating the different input signals, the PCM sends a control signal to the A/C clutch relay, which engages and disengages the compressor clutch. The PCM input signals come from the blower motor switch via the evaporator temperature sensor (vehicles with manual temperature control), via the A/C module (vehicles with automatic temperature control), the A/C pressure converter sensor and the PCM. Overview - air conditioning system 4 - High pressure charging connection 5 - A/C pressure converter sensor 6 - Low pressure charging connection Service evaporator The evaporator is located on the right-hand side of the climate control housing (LHD and RHD). It can be removed and installed with the climate control housing still installed in the vehicle, although the heat exchanger does need to be removed first. The refrigerant lines of the production evaporator must be sawn through during removal. An evaporator with separate refrigerant lines is installed in service. Electronic refrigerant compressor control valve On vehicles with a 2.5L Duratec-ST (VI5) engine a refrigerant compressor with electronic control valve is used. The control valve regulates the delivery rate of the refrigerant compressor according to the request received from the A/C module. | 
