Fig. 12.2. Schematic diagram of the refrigerant flow in the air conditioning system: 1 – combined pressure sensor; 2 – section of high pressure pipeline; 3 – receiver-dryer; 4 – high pressure line service valve; 5 – condenser (air conditioning radiator); 6 – condenser and radiator fan of the cooling system; 7 – air conditioning compressor; 8 – low pressure pipeline section; 9 – Low pressure line service valve; 10 – heater fan; 11 – evaporator; 12 – thermostatic valve.
Ford Mondeo cars are equipped with a compressor-type air conditioning system. The heater units and the air conditioner evaporator heat exchanger are made in one block. The air conditioning system controls are located on the panel, common with the heater controls.
The basic diagram of the movement of refrigerant in the air conditioning system is shown in Fig. 12.2.
The compressor is mounted on the engine and is driven by a poly-V belt.
NOTE: On vehicles with 1.6L Duratec-16V Ti-VCT engines (110 and 125 hp); 2.0 l Duratec-НЕ (145 hp); 2.3 l Duratec-НЕ (161 hp); 1.8 L Duratorq-TDCi (100 and 125 hp); 2.0 l Duratorq-TDCi (140 hp) and 2.2 l Duratorq-TDCi (170 hp) are equipped with Visteon VS16 compressors, and with 2.5 l Duratec-VI5 engines (220 hp) – Zexel KC88 compressors. Both compressor models have a similar design and differ mainly in the shape and location of the mounting elements.
The compressor ensures the circulation of the refrigerant in the system. The compressor shaft is mounted in an aluminum housing on two needle bearings and is sealed on the drive pulley side with a seal.
The compressor drive pulley is mounted on a double-row ball bearing and rotates continuously when the engine is running. When the air conditioner is turned on, torque is transmitted from the pulley to the compressor shaft through a friction clutch with an electromagnetic drive.
USEFUL TIP: When the air conditioner is turned on, a click is heard - this is the clutch, under the action of an electromagnet, engaging with the drive pulley, and the compressor rotor begins to rotate.
This is if the system is working properly.
But during the operation of the air conditioner, several types of compressor malfunctions may occur.
1. If the clutch makes strange sounds when rotating, heats up, or smells like burning when the air conditioner is off, then its bearing has probably started to deteriorate. In this case, the bearing must be replaced. In some advanced cases, it may be necessary to replace the compressor clutch or its components.
2. If there is no click after turning on the air conditioner, then it is possible: a - there is a refrigerant leak, and the electrical control circuit is blocking the compressor from turning on; b – the pressure sensor in the system is out of order; in - the electrical control circuit is broken; g – electromagnetic clutch coil burned out; d – the engine control unit for some reason blocked the compressor from turning on.
3. If the clutch rotates easily and freely, but when the air conditioner is turned on, there are obvious extraneous noises or even the engine stalls, then most likely the compressor is jammed. The internal pump part of the compressor cannot be repaired. In this case, the compressor will have to be replaced.
4. And the last, most unpleasant option. A click is heard, the clutch easily rotates the compressor shaft. But there is no air cooling in the cabin. Perhaps the compressor is running idle.
In this case, only an experienced specialist with control and diagnostic equipment can determine the malfunction. If your car's compressor has been diagnosed with "No compression", you should be absolutely sure that it was diagnosed by a good specialist. In case of doubt, you can run diagnostics again and make sure that considerable costs for purchasing and replacing the compressor are indeed inevitable.
In all these cases, an accurate answer to the cause of the malfunction can only be given by conducting a full diagnosis in a specialized service center for repairing car air conditioners.
Condenser (air conditioning radiator) multi-flow type is located in front of the engine cooling system radiator.
It is secured using four supports installed in brackets on the radiator tanks.
The condenser honeycombs are made of flat thin-walled aluminum tubes with internal longitudinal partitions for rigidity and external finning to improve heat exchange. The tanks are aluminum, with flanges for connecting the tubes. The tanks are divided into sections by height, so the flow of refrigerant changes direction several times as it passes through the condenser. In the condenser, condensation of the vapors of the refrigerant compressed by the compressor occurs, and the heat released in this process is removed into the surrounding air.
When the air conditioner is turned on, the engine control unit turns on the power supply circuit of the additional electric fan of the engine cooling radiator. This improves heat exchange in the condenser and reduces the pressure in the air conditioning system.
USEFUL TIP: At least once a year, preferably before the start of summer operation, wash the fins A honeycomb condenser from adhering dirt, dust and anti-icing reagents B. This will improve heat exchange, reduce pressure in the system and increase the service life of the system elements.
Do not use high-pressure water jet cleaners to clean the condenser. This may cause damage IN thin-walled finned plates.
Even with regular washing, the need to replace the condenser arises much more often than desired. The fact is that it is the first to take on the flow of anti-icing reagents, dirt and pebbles from the road.
And its tubes are thin... In most cases, the condenser is damaged by corrosion in the third or fourth year of operation.
If the condenser has lost its tightness as a result of corrosion, then repairing it is more expensive. Even if the argon welding master manages to patch the hole, a leak may soon appear in another place. By the way, the pressure in the system on hot days can reach 25-30 atm.
In addition, it should be remembered that the condenser tube has a complex structure - it is divided into channels by partitions along the length. And there is a high probability that after welding, some of the channels will be blocked. Accordingly, the dissipated power will drop and the operation of the air conditioner will deteriorate, especially when standing in traffic jams and in hot weather.
Besides, after each experiment with welding the condenser, you will have to pay for welding, installation and dismantling of the condenser and filling the system with refrigerant. So it is better to install a new one right away, although instead of an expensive original one, you can buy a cheaper condenser from authorized manufacturers of spare parts.
Evaporator is located in the heating and air conditioning system block. The evaporator is made of aluminum tubes with external fins to improve heat exchange.
Passing through the evaporator tubes, the boiling refrigerant actively absorbs heat from the air blowing on the outer finned surface of the tubes. The air is cooled and supplied to the car interior by a fan.
To prevent evaporator icing, some vehicles have an evaporator temperature sensor. This sensor measures the surface temperature of the evaporator fins. If the measured temperature falls below +2°C, the air conditioning compressor clutch is disengaged. If the temperature rises above +4°C, the compressor is turned on again. The sensor signal on units with manual temperature control is transmitted via the multifunction electronic module (GEM) and the CAN bus to the engine control unit, which then engages or disengages the compressor clutch.
On units with automatic temperature control, the sensor signal is first transmitted to the air conditioning control module and then via the CAN bus to the engine control unit, which then engages or disengages the compressor clutch.
NOTE: When the air passing through the evaporator is cooled, the water vapor contained in it condenses. The condensate drains through the drain pipe under the bottom of the car. If the ambient air humidity is high, a puddle of water may form under the car, which is an indirect sign that the air conditioning system is working properly.
USEFUL TIP: During vehicle operation, particles of road dust and dirt settle on the outer surface of the evaporator, which is wet from condensation.
This layer becomes an excellent environment for the life and rapid reproduction of putrefactive bacteria and fungal cultures. Over time, an unpleasant smell appears in the car. It is especially noticeable when the air conditioner is turned off and in humid weather.
In order to minimize the risk of this problem, when buying a new car, it is necessary to carry out preventive treatment of the evaporator with special chemicals, regularly replace the cabin filter and clean the drainage tube. If, despite the measures taken, the smell still appears, contact a specialized service for repairing car air conditioners for disinfection or washing of the evaporator.
If the contamination is very severe, the evaporator will have to be replaced.
Access to the evaporator is on the right side of the climate control unit. The evaporator can be removed and installed without removing the climate control unit housing. To do this, you must first remove the heat exchanger (radiator) of the heater. When removing the factory-installed air conditioner evaporator, its connecting pipes must be sawed off. During repairs, an evaporator with separate removable pipes is installed.
Thermostatic expansion valve block type is located in the evaporator body. The valve is attached to the pipelines using flange connections. After passing through the throttling hole in the valve body, the liquid refrigerant sharply reduces pressure and begins to boil. A control element is installed in the valve body, changing the flow section of the throttling hole depending on the pressure and temperature of the refrigerant. The control element is adjusted at the manufacturer and is not subject to adjustment during operation.
WARNING: If aluminum or plastic particles are found in the throttling hole of the valve, the pump part of the compressor has been destroyed. Replacing only the thermostatic valve in this case will not give a positive result. The compressor will need to be replaced with a system flush. This is a fairly labor-intensive procedure that can only be performed in a specialized service center using special technological equipment.
Receiver-dryer 3 (see Fig. 12.2) is installed on the condenser on the left side and forms a non-separable unit with it. Inside the housing there is a filter element (cartridge) filled with desiccant granules (silica gel). The liquefied refrigerant passing through the receiver is cleaned of possible impurities, dirt and moisture. The receiver housing is made of aluminum alloy. In the lower part of the housing there is an opening for replacing the filter element.
The hole is closed with a threaded plug A with a sealing gasket.
WARNING: In case of repair or replacement of air conditioning system components, if it was in an open state (any units were removed, pipelines were damaged, etc.), the receiver-dryer cartridge must be replaced. Otherwise, after filling the system, the refrigerant will not be dried and acids may form inside the system, which will destroy the air conditioner components from the inside.
Pipelines connect all elements of the air conditioning system into a single hermetic circuit. The pipelines and their mounting flanges are made of aluminum alloys.
Fig. 12.3. Flexible insert hose design: 1 – outer protective sheath; 2 – fabric cord of the power frame; 3 – plastic sealing layer; 4 – inner oil-resistant layer
To connect mutually moving elements of the system, pipelines in some sections have flexible inserts (Fig. 12.3) made of synthetic materials.
In the places where individual system elements are connected, neoprene circular cross-section sealing rings are installed. During system repairs, when pipeline sections are disconnected, the sealing rings must be replaced. Tighten the threaded connections of the pipelines with the recommended torque. Weak or excessively strong tightening leads to deformation of the sealing surfaces and refrigerant leakage.
Two service valves for connecting diagnostic and filling equipment are located on the pipelines.
The valves are covered with threaded caps to protect them from dirt.
NOTE: This is how the high pressure line service valves are located on the pipelines…
…and low B pressure.
The valves are equipped with valve cores that are similar in design to the valve cores of the tire wheels, but differ from them in size.
A special key is used to unscrew and screw in the valve cores.
WARNING: It is prohibited to check for the presence of refrigerant in the system by pressing on the service valve spools, since after such a check the valve spool may not close completely and refrigerant will leak from the system!
Pressure sensoris installed on a section of the high-pressure pipeline. Based on the sensor signals, the engine electronic control unit forcibly switches off the air conditioner compressor in the event of a system depressurization or an emergency increase in pressure in it in order to protect the compressor from overloads.
Panel of the manual or automatic (depending on the configuration) control unit for the ventilation, heating and air conditioning systeminstalled on the instrument panel console.
Coolant. An information plate indicating the type and quantity of coolant used in the system is glued to the surface of the upper casing of the radiator grille.
It is strictly forbidden to use other types of refrigerants in the system. A special oil (PAG) is added to the refrigerant to lubricate the compressor.
Filling volumes of the system, g
Refrigerant R134a:
with Visteon VS16 compressor……….520±15
with compressor Zexel KC88………….590±15
Oil……………………………………………..200±10
NOTE: During the operation of the car air conditioner, situations arise periodically when the air conditioning system needs to be serviced or repaired. Modern diagnostic and repair equipment is used for this. The most common situation is the depressurization of the system and the release of refrigerant from it.
Highly sensitive halogen leak detectors with sound indication are used to detect leaks.
In some complex cases, the so-called ultraviolet diagnostics method of air conditioning system tightness is used.
The method consists of introducing a special dye into the system in microdoses.
In places of micro leaks, the dye, together with the refrigerant, gradually comes out onto the surface of the system elements.
During inspection of the system, under the influence of ultraviolet rays from a special lamp, the dye begins to glow (fluoresce)…
…and the refrigerant leaks become visible.
It should be noted that the dye does not have any negative impact on the system. It can be in the coolant and circulate in the system for as long as desired and serve its purpose only when a leak occurs.
After repairing the car air conditioner, it is necessary to vacuum and fill the system with the appropriate refrigerant (R134a).
The volume of air conditioning filling for each car model is individual.
To perform a high-quality refueling of the car air conditioner, you need:
– precision manometric blocks with special connecting tips;
– two-stage vacuum pump for complete removal of air and water vapor from the system;
– high-precision (division value ±5 g) scales for dosing the amount of refrigerant to be filled.
Due to the specific features of air conditioning system repair, this section describes only the work on removing and installing individual elements and the system control unit. Work related to filling the system with refrigerant should be carried out in specialized service centers.
WARNING: The air conditioning system is filled with refrigerant under high pressure. If liquid refrigerant comes into contact with human skin, it can cause severe frostbite. Therefore, if possible, carry out all work related to servicing, repair or dismantling of air conditioning system components in specialized service centers equipped with professional technological equipment. When carrying out work on your own, take precautions.
[The text was obtained in its entirety from the specified website: www.fordbook.ru]