Automotive training manual pdf

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As this liquid passes through the evaporator coil, heat moves from Same design as the serpentine the warm air blowing across the evaporator condenser but approximately five times fins into cooler refrigerant. This air that has deeper. This causes the refrigerant to change from a low- pressure cold liquid into a cold vapor.

Latent heat of evaporation. As the warmer air blows across the evaporator fins, moisture contained in that air humidity will condense on the cooler evaporator fins.

This is accomplished by the thermal expansion 7. F1 Pressures in control As shown in the illustration, the TXV controls the refrigerant flow by using a 2. Sealed tube filled with refrigerant. This 4. The capillary tube sensing bulb 3 is attached to the evaporator 6.

F3 outlet tube surface. F2 - Pressure compensation tube 9. F2 This is a hollow tube connected to the evaporator outlet tube and senses the High Pressure liquid pressure of the Ra refrigerant leaving the evaporator coil. Other TX valves may 1. From Filter Drier 6.

Spring not use this tube as pressure is provided 2. To Evaporator Inlet 7. Diaphragm internally within the valve. Capillary tube 8. Refrigerant 4. Metering Orifice 9. Pressure Compensating F3 - Pressure spring 5. Ball valve Tube This spring 6 is located under the ball valve 5. TXV - Open Operation 8. Open 7. When the evaporator outlet tube F1 temperature increases, the refrigerant 3 in the capillary tube expands, forcing the diaphragm 7 downwards and thus 2.

Pressure 5. Closed As the evaporator outlet tube becomes cooler, the refrigerant in the capillary tube 3 contracts. Forces F2 and F3 cause the diaphragm 7 and pin A to move upward 6. F2 flow. The outlet tube gets warmer and the High Pressure liquid process starts over. Operation of the block It is sensed by changes in the refrigerant temperature and pressure Low passing from the evaporator outlet through Pressure the block valve.

Liquid 1. As the refrigerant from the outlet side of the evaporator passes over the sensing element 12 , expansion or contraction of the High refrigerant takes place causing the activating 5.

Pressure pin 8 to move the ball valve 6 away or Liquid 6. This allows 8. F3 evaporator coil inlet. Pressures in control 1. From Filter Drier 8. Activating Pin As shown in the illustration, the block valve 2. To Evaporator Inlet 9. Refrigerant controls refrigerant flow by using a system of 3. From Evaporator Pressure Compensation opposing pressures which we will call: 4. To Compressor under Diaphragm 5. Metering Orifice Metallic Diaphragm 6.

Ball Sensing Element F1 - Temperature sensing 7. Spring This is a sealed diaphragm and sensor containing refrigerant. As refrigerant leaving the evaporator coil outlet passes over TXV - Closed sensing element 12 the refrigerant 9 F2 F2 - Pressure compensation This is a passage 10 in the block valve 3.

F3 - Pressure spring This spring 7 is located under the ball valve 6 and acts as an opposing force trying to 5. High Pressure move the ball valve towards the metering 6. Liquid orifice 12 and to reduce refrigerant flow to 7. The thermal expansion valve TXV values are preset at factory to compensate for the super heat. This causes a pressure drop and temperature drop in the Ra entering the evaporator. The rate of flow depends on the pressure difference across the restriction. A fine gauze filter is located at the inlet and outlet sides of the orifice tube to filter any contaminates from passing onto the evaporator.

The silica gel beads desiccant located in the FDR absorb small quantities of moisture thus preventing acid establishment. Strainer Most Ra filter dryers have NO sight glass. This is because at approximately C refrigerant temperature the PAG oil will foam giving a false impression of low gas charge. If the FDR does utilize a sight glass ensure correct diagnosis when viewing. Note: Ensure the connection indicated with the word "IN" is connected to the condenser outlet.

The normal process of the Orifice Tube system works when Ra leaves the evaporator coil as a mixture of vapor and liquid. This liquid enters the accumulator and falls to the bottom.

The vapor rises to the top and continues onto compressor. The liquid Ra in the bottom of the accumulator gradually vaporizes off. This vapor rises, then pulls into the compressor. Other manufacturers could use "O" rings of a different color and size. Ensure that only the approved "O" ring is used for the type of system being serviced or repaired.

This is to reduce the normal refrigerant leakage that would naturally occur through the porosity of rubber hoses. The PAG oil and hydrogen contained in the Ra causes the normal R12 nitrile hoses to rapidly deteriorate. A plastic cap with rubber seal is used to close the charge port opening and avoid leaking. A dedicated design of charging valve has also been developed to suit the Ra charging ports.

Most schrader valves will leak slightly. Ensure that the plastic protection cap is fitted. Schrader valves designed for Ra must only be used in Ra systems. This is because of the seal material used. If an "under" or "over" system pressure occurs the pressure switch will "open circuit" breaking the circuit to the compressor clutch.

Also an RPM increase generally takes place to avoid engine stall whilst at idle. These coiled wires are of varied thickness. The current flows through either one or a combination of all the coils. The resistance of the coil s alter the blower speeds. The highest blower speed when selected Fan Speed is normally from direct battery voltage via Resistance a relay. Coils Electronic Electronic Type The function of the electronic controller is Electronic to convert low current signals from the Modiual ECM to a higher current, varying the voltage to the blower motor.

Blower speeds may be infinity variable and usually can use up to 13 speeds. This type of speed controller is normally used with the electronic climate control ECC system. The highest blower speed Heat when selected is normally from direct Sink battery voltage via a relay.

When the temperature of the evaporator coil approaches freezing Switch 00C , this temperature is sensed by the Point thermostat capillary tube which is in contact with the evaporator fins. The capillary tube Bellows contains refrigerant which expands or Filled with contracts depending on the temperature on Refrigerant this tube.

When the evaporator temperature rises again to a preset point 4 - 5 0C the thermostat points then close. The refrigerant in the capillary tube has expanded sensing a warmer evaporator coil and the electrical circuit is re- established to the compressor clutch. The thermistor is a sensing probe but unlike the thermostat capillary tube it senses the air temperature coming off the evaporator coil.

Thermistor Electrical wiring containing a sensor which is a NTC resistor. Negative Temperature Co-efficient. Thermistor Amplifier A small electronic device containing a circuit board and electrical components.

Economy mode This function is normally associated with the use of a thermistor amplifier. This means the compressor stays on for a lesser time, decreasing engine load and improving fuel economy and engine performance. This pressure switch is electrically connected in series with the compressor clutch.

Once the low side pressure reaches approximately kPa, the compressor clutch is deactivated by the pressure switch opening. Once the compressor is deactivated the low pressure rises followed by the evaporator coil temperature rising. At a pre-determined low pressure point, the pressure switch reactivates the compressor clutch. The evaporator temperature lowers again and the compressor re-engages. Note: Normally a low pressure cut off switch is not used with a pressure cycling switch as the pressure cycling switch is located on the low side.

It serves as a low pressure cut off also. During these periods, the control valve maintains a bleed from crankcase to suction. Crankcase pressure is therefore equal to suction pressure. The wobble plate angle, and therefore compressor displacement is at its maximum.

The control valve maintains a bleed from discharge to crankcase and prevents a bleed from crankcase to suction. The wobble plate angle, and therefore compressor displacement is reduced or minimized. This magnet field is constant as long as the clutch is applied.

When the power is removed the magnetic field collapses and creates high voltage spikes. These spikes are harmful to the ECM and must be prevented.

A diode placed across the clutch coil provides a path to ground. This diode is usually taped inside the clutch coil connector. Diode Compressor Thermal Clutch Protection Switch Thermal protection switch The thermal protection switch is normally located on the compressor housing.

This protection switch is used to prevent compressor damage through internal friction. This switch senses the compressor case temperature and once this case temperature reaches a predetermined figure the electrical circuit to the compressor clutch is interrupted.

As the thermal protection switch is connected in series with the compressor clutch once the Fixed compressor case temperature lowers to a Contact predetermined figure the compressor clutch is Bimetalic then re-energized. Condenser fan control kPa Medium pressure example Used to engage the condenser fan at a pre- determined refrigerant pressure.

Example: Condenser fan high speed activation at kPa refrigerant pressure. These switches can be individual or a combination of the two or even three pressure ranges.

It provides a 0. In operation the transducer sensor applies pressure via the deflection of a two piece ceramic diaphragm with one half being a parallel plate capacitor. Changes in capacitance influenced by the refrigerant pressure under the ceramic diaphragm are converted to an analog output by the transducer integral signal electronics. The pressure transducer's electronics are on a flexible circuit board contained in the upper section of the transducer and provide linear calibration of the capacitance signal from the ceramic sensing diaphragm.

Benefits of using the pressure transducer over a normal type pressure switch is that the transducer is constantly monitoring the pressures and sending signals to the electronic control module ECM , unlike the normal type pressure switch that has an upper and lower cut out points. Shown below is an example of the difference in a circuit with and without a relay. This sensor sends a signal to the electrical climate control module ECCM indicating the strength of the sunlight sunload which influences the vehicle interior temperature.

If the sunload is high as signaled by the sunload sensor the ECCM will activate the highest blower fan speed and maximum cooling to compensate for this additional radiated heat load.

Likewise, if the sunload is low cloud cover as sensed by the sunload sensor, the ECCM will reduce the blower fan speed and the system will not operate at maximum cooling. Ambient temperature sensor The ambient temperature sensor is a negative coefficient resistor NTC with low voltage input.

The sensor alters resistance depending on the ambient air temperature surrounding it. The sensor is located in the ambient air stream normally behind the bumper bar or front grille area. This sensor is used to monitor the outside temperature and is interconnected to a visual display in the instrument panel. This door is located above the heater core and in the full cold position, completely covers the heater core.

This stops the flow of coolant to the heater core by keeping the heater tap closed. Once heating has been selected, the vacuum is exhausted from the vacuum circuit via a vacuum switch, to the heater tap and the hot coolant then flows Vacuum From Switch Vacuum through to the heater core.

When the vacuum is removed, the spring pushes the diaphragm and Vacuum Applied connecting rod back to original position. Mode Direction A vacuum switch attached to the mode Control Mode control knob redirects vacuum to the Vacuum Control desired vacuum actuator. It comprises of small electrical motor, gears of varying sizes, a drive shaft and a printed circuit board. It is attached by means of a drive shaft to the air mix or temperature mode door main shaft. This motor regulates the temperature by moving the door closer to cooler or further from hooter the heater core.

Variable low voltage signals are sent from the electronic climate control module ECC to move the air mix motor - which in turn moves the temperature mode door, to a predetermined position to regulate the vehicle interior temperature. Vacuum solenoid pack Actuator This method for operating the vacuum actuators is normally used in conjunction with the electronic climate control system ECC. This type of climatic control is fully electronic.

The vacuum actuators used for various air distribution modes are indirectly engaged and disengaged electronically via the vacuum solenoid pack. The solenoid pack consists of a group of electrically activated vacuum solenoid valves using a common printed circuit board while enclosed in a single housing. Each solenoid is allotted to a vacuum actuator or vacuum valve heater valve. Once the vacuum solenoid is energized by the ECC, an Vacuum Solenoid engine supplied vacuum can then flow through Pack the solenoid valve to the relevant vacuum actuator to operate a mode.

Likewise, once the vacuum solenoid is de-energized it then vents the vacuum from the line and actuator into the atmosphere. The major difference being that the ECC system can maintain a preset level of cooling or heating selected by the vehicle operator once the automatic mode is selected.

Electronic sensoring devices allow the ECC to respond to various changes in sunload, interior cabin temperature and ambient temperature. The ECC system will adjust automatically to any temperature and climatic changes to keep the vehicle cabin interior within the pre-selected temperature range. An additional benefit of the ECC system is a self-diagnostic function which when used will greatly reduce the time spent locating system faults.

No direct "drop in" replacement is available, even alternatives such as ternary blends require the replacement of components such as "O" rings on some systems, filter dryers or accumulators. Cost will be a very important issue if an Ra retrofit is to be undertaken, but do not sacrifice performance and reliability for the sake of cost.

As further documented there will be slight temperature and pressure increases within the system. Do you replace the condenser with more efficient design? Explain associated costs to the owner. Take note of the pressure and temperature readings. Flushing option - If when removing components contamination is found i. Flush all remaining components with a recovery device. Write on labels all fitment information required in ballpoint pen. Performance Check - Take pressure and center vent temperature readings, compare to the "baseline" information taken in step 2.

Road Test - Carry out road test, again check performance in the various fan speeds and mode positions. Ensure if in an extended idle situation the compressor does not fast cycle on the high-pressure switch high-pressure problem. Hand over - Explain to customer what exactly has been replaced, and any warranty implications. Important notes: - Use only a specified Ra Recovery and Recycling equipment.

Ariazone - Mini Recovery Unit The Ariazone is lightweight recovery system for the on site mobile technician or small workshop operator. This system has been designed to be very user friendly and efficient for every user. Simply connect the Ariazone to the air conditioning system switch on and walk away.

The will take care to the rest. Moisture in a refrigerant system While it is important to realize that moisture in a refrigerant system is the underlying cause of most problems and complaints, it is equally important to learn why.

Basically, moisture can be classified as visible and invisible. Occasionally, liquid water is found in system, but this is unusual. Invisible moisture, or water vapor, is culprit which causes the greatest trouble in refrigeration and air conditioning systems. A single drop of water may look harmless, but to a refrigerant system, it is a monster, the number one enemy of the service technicians.

What makes it so formidable is the fact that moisture enters a system easily and is hard to remove. Here is what it does to a system: First, it creates "freeze-ups". Moisture will be picked up by the refrigerant and be transported through refrigerant lines in a fine mist which forms ice crystals at the point of expansion expansion valve.

Ice crystals retard or stop the flow of the refrigerant, causing loss of cooling. As the expansion valve warms, due to lack of refrigerant, the ice melts and passes through the expansion valve. The refrigerant will then start again until the moisture returns to the expansion valve and once more builds ice crystals.

The result is intermittent cooling. Whether a "freeze-up" actually occurs depends primarily upon the amount of water and the size of the ice particles formed. But a "freeze-up" is not the only problem caused by moisture. It can also cause corrosion, which can present serious trouble. Moisture in form of water can cause corrosion after a period of time. However, moisture mixed with refrigerant creates much more corrosion trouble.

Refrigerant such as R12, containing chlorine, will slowly hydrolyze with water and form hydrochloric acids. This acid greatly increases the corrosion of metals and could corrode copper plating. Heat increases the rate of corrosion due to acids because higher temperatures accelerate the acid-forming process.

The acid attacks all the materials it contacts. Refrigerant oil presents another problem caused by moisture. Refrigerant oil is an exception to the rule that "oil and water don't mix". In fact, some refrigerant oil attracts moisture and will absorb it rapidly if left open to the atmosphere.

Water-formed acid mixes with refrigerant oil, forming a closely bonded mixture of fine globules. The effect is called "sludging" and greatly reduces the oil's lubrication ability. Corrosion becomes troublesome from the operating standpoint when metallic surfaces are eaten away and a solid, detachable product is formed.

This formation is also known as a "sludge". Sludge can cause a variety of problems. It will plug fine strainers, expansion valves and capillary tubes. And because it usually contains acids, sludge corrodes whatever it clings to, accelerating system damage. A deep vacuum is capable of removing all moisture from a 4 5 hermetic system by reducing internal system pressure to 3 6 the boiling point of water at normal temperatures.

The term "high vacuum" describes the same condition inside a closed system. Factors affecting the speed at which a pump can dehydrate a refrigerant system Several factors influence the "pumping speed" of a high vacuum pump and thus the time required to remove all moisture from a refrigerant system. Some of the most important are: the cubic capacity of the system, the ambient temperature present, internal restrictions within the system, external restrictions between the system and vacuum source and the size of the pump, but more important how low a vacuum can it pull down.

The lower number in microns, the better the pump. Vacuum Station - Ariazone The Ariazone is a Large display, system which conveniently discharge and allows the technician to test suction gauges the air-conditioning systems working pressures, evacuate and inject oil into the air- Oil injection conditioning system and unit features a graduated oil injection unit.

They are: By volume - using a graduated charging dial cylinder, By weight - using electronic scale with LCD read out. The new unit has been designed for Digital ease of operation, accuracy and durability. Display Features: Oil Container - Monitors suction and discharge system pressures. Refrigeant - Displays amount of refrigerant in storage Cylinder cylinder.

Large 85 lit. Operations are entered into an electronic keypad. These include: - Charging to the specified amount. The unit will automatically carry out all the pre-selected operations. A once difficult process is now stream-lined and automatically completed by the Ariazone system. The following safety precautions must be followed: - Always wear eye protection. Hot water on the air conditioning pipes and tubes could create thermal expansion of the refrigerant contained in the system.

Leak detection methods Visual leak detection When a refrigerant leak occurs, it is common in some cases for the lubricant oil to escape with the refrigerant. The pressure of oil and encrusted dust around hose fittings, joints and components will indicate a leakage point. Electronic leak detector 5mm These leak detectors operate in various ways. The most common being that when the unit is turned on, a low ticking sound can be heard and once the probe Sensing locates a leak, the ticking sound Tip increases to a high pitched noise.

This can be achieved by moving the sensing tip slowly around the underside of components and fittings at a distance of approximately 5 mm. DO NOT allow the sensing tip to contact components or fittings as false readings and tip damage will occur.

If a leak is evident, the colored dye glows bright. This method is exceptionally good for pin pointing a small leak. Failure to do so could void the manufacturer warranty. This is normally found in the particular vehicle workshop manual. Likewise, remove the oil from the new compressor, refill this new compressor with the same quantity of oil drained from the old compressor.

On compressors without inspection plugs, add oil to compressor through the discharge and suction ports, turn the compressor hub Condenser several times by hand to make sure no oil is trapped in the compressor chambers. Use the new clean oil removed from the new compressor plus 10cc to allow for any internal oil.

We recommend flushing individual components or system sections with refrigerant Ra, this refrigerant should be collected via a recovering machine and can be used again. Components or tube connections mostly self-made will have to be used and flushing carried out with the refrigerant in liquid from i.