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Heating System 

Basic Climate Control 

Thermostat 

• 

When starting a cold engine, the thermostat stays closed to ensure that the coolant flows 
only through the ‘small circuit’. This ensures that the engine reaches its operating 
temperature as quickly as possible, and that heat is available for the heater core to heat 
up the air as quickly as possible. When the engine temperature exceeds a certain value, 
the thermostat opens to allow the coolant to flow through the radiator (‘big circuit’). In this 
way, the optimum engine temperature is maintained and overheating of the engine is 
prevented. 

 

Heater Core 

• 

The heater core has essentially the opposite function of the evaporator. The hot coolant 
flowing through the tubes of the heater core releases its heat to the air passing through 
the fins of the heater core. The fins, which are brazed to the tubes, allow for efficient 
heat transfer between the hot coolant and the cool air. The air mix door will determine 
how much of the airflow passes through the fins of the heater core, and accordingly how 
much warmth will be transferred to the air. The control strategy is covered in depth in the 
‘Advanced Climate Control’ course.  

 

Water Pump 

• 

The water pump is driven by the engine and circulates the coolant through the system.  

 

Radiator 

• 

The radiator functions just like the heater core, except that it is much larger to allow it to 
release the engine heat to the air passing through the fins.  

 
 

04-2 Curriculum 

Training 

Содержание CT-L1005

Страница 1: ...Training Manual Basic Climate Control CT L1005...

Страница 2: ...ation data and descriptive text in this issue to the best of our knowledge were correct at the time of going to print No liability can be accepted for any inaccuracies or omissions in this publication...

Страница 3: ...ironmental Impact 02 12 Compressor Oil 02 13 Moisture in the A C System 02 13 A C System 03 1 System Overview 03 1 A C System with Expansion Valve 03 3 Parts Location 03 3 Compressor 03 4 Vane Rotary...

Страница 4: ...Heating System 04 1 System Overview 04 1 Thermostat 04 2 Heater Core 04 2 Water Pump 04 2 Radiator 04 2 Diagnosis and Repair 05 1 Pressure Gauges 05 1 Refrigerant Pressure Check 05 2 Leak Testing 05 4...

Страница 5: ...agnosing and repairing climate control system related concerns requires working with a refrigerant under pressure Improper handling of the refrigerant could lead to serious injuries Follow the safety...

Страница 6: ...iagnosis and Repair NOTE The data tables and procedures presented in this training manual serve only as examples They are taken from the service literature and subjected to major or minor changes over...

Страница 7: ...eople find it comfortable based on the air temperature and relative humidity There are also other factors not shown on this graph that affect our comfort such as how clean the air is and if there is a...

Страница 8: ...g clothes off and putting clothes on So a vehicle has a climate control system to allow the driver to create a comfortable climate To allow the driver to do this it has to be possible to change the tw...

Страница 9: ...ambient temperature of the room The heat travels from the warmer surroundings to the cooler water L1005_001 In the second example a hot cup of coffee is brought into a warm room The coffee gives off t...

Страница 10: ...room The heater core gives its heat up to the outside air that comes in contact with the fins The heat travels from the warm heater core to the cold air Unlike the coffee in our example the heater cor...

Страница 11: ...uid As the warm air comes in contact with the fins of the evaporator the heat from the warm air is conducted through the metal fins and warms the refrigerant flowing through the internal passageways T...

Страница 12: ...ll of the ice is melted does the temperature start to rise again in direct relation to the amount of heat added stage 3 This is because the energy added is no longer required to change the ice to wate...

Страница 13: ...als L1005_022 X Heat energy Y Temperature 1 Ice being warmed 5 Steam being warmed 2 Ice changing to water 6 Latent heat of fusion 3 Water being warmed 7 Latent heat of vaporization 4 Water changing to...

Страница 14: ...air this is determined by the dew point which depends on the current air temperature and the relative humidity of the air Operating the A C allows the evaporator to cool down and for the moisture in t...

Страница 15: ...Heating Ventilation Air Conditioning system filters both the fresh air and the recirculated air A certain amount of smaller particles that pass the filter are also trapped in the condensed water which...

Страница 16: ...NOTE Older Mazda vehicles use R12 refrigerant which must not be used anymore In addition R12 and R134a must not be mixed Pressure Temperature Relationship of R134a This chart shows the relationship be...

Страница 17: ...the pressure will then increase rapidly and the container could rupture CAUTION Filling a container more than 60 and storing a container near sources of heat or in direct sunlight can cause serious i...

Страница 18: ...king in a pit or other low lying area while servicing the A C is not recommended because large amounts of released refrigerant could displace the air and cause suffocation While R134a is not flammable...

Страница 19: ...servicing a vehicle the correct oil needs to be put into the A C system NOTE Compressor oil needs to be properly disposed of just like any other environmentally harmful fluids brake fluid engine coola...

Страница 20: ...Fundamentals Basic Climate Control Notes 02 14 Curriculum Training...

Страница 21: ...em from the low pressure side and throttles the refrigerant bringing it to its coldest temperature The other system used is the fixed orifice system which has the same function as the expansion valve...

Страница 22: ...air coming in contact with the fins of the condenser absorbs the heat from the refrigerant cooling it and liquifying it The liquid then travels to the expansion valve or the fixed orifice where it is...

Страница 23: ...essure gas This gas then moves into the compressor where the pressure and temperature are increased The cycle then continues A C System with Expansion Valve Parts Location L1005_029 1 Compressor 6 Rig...

Страница 24: ...ad from the engine see the section Control The compressor is one of the two components that separate the high pressure side of the A C system from the low pressure side Compression Plotted on the Refr...

Страница 25: ...entrically mounted rotor with vanes that are thrown out by centrifugal force to create a seal against the housing As the rotor moves through its eccentric path the chamber becomes smaller compressing...

Страница 26: ...helix mounted so that the moving helix creates a chamber that draws the refrigerant in seals the chamber off and compresses the refrigerant L1005_036 1 Thrust plate 5 Moving helix 2 Fixed helix 6 Ball...

Страница 27: ...mounted at an angle on a shaft The swash plate moves a number of double acting pistons to draw in and compress the refrigerant Reed valves control the induction and compression of the refrigerant L10...

Страница 28: ...below Point 2 represents the stage in the A C system after the refrigerant has left the compressor and before it enters the condenser At this point the refrigerant is a high pressure high temperature...

Страница 29: ...Tube Condenser The refrigerant flows through tubes laid out in a serpentine path The fins brazed to the tubes increase the transfer of heat from the refrigerant to the ambient air L1005_042 1 Fins 2 R...

Страница 30: ...aller channels resulting in more heat transfer than in a fin and tube condenser In addition the refrigerant is sent through the condenser in a parallel flow increasing the cooling performance even mor...

Страница 31: ...denser Incorporating the receiver drier into the condenser ensures that at this last sub cooling stage no 4 in the illustration only liquid refrigerant is being cooled NOTE Depending on the model the...

Страница 32: ...oir the liquid refrigerant in the receiver drier helps to compensate when there are changes in the cooling demands and the amount of liquid refrigerant needed in the evaporator fluctuates To make sure...

Страница 33: ...n 3 hours the desiccant will be saturated and the surplus moisture will cause the PAG oil to break down Any water not able to be trapped by the desiccant can also mix with the refrigerant creating a c...

Страница 34: ...rant through the expansion valve In this way the heat absorbing performance of the evaporator is adapted to the actual demand Expansion Plotted on the Refrigerant Curve L1005_023c X Pressure Y Tempera...

Страница 35: ...more refrigerant in the evaporator to absorb heat and the refrigerant temperature will decrease Then the process continues Expansion Valve L1005_011 1 Diaphragm 8 Spring force 2 Reference chamber fill...

Страница 36: ...ling through the inside of the evaporator The heat is absorbed by the refrigerant as it changes its state from a liquid to a gas Vaporisation Plotted on the Refrigerant Curve L1005_023d X Pressure Y T...

Страница 37: ...The refrigerant flows through tubes that have fins attached to them to allow for heat dissipation Internal flow of refrigerant through the evaporator L1005_010 1 Liquid refrigerant from expansion valv...

Страница 38: ...It is normal that during operation of the A C a pool of water may appear underneath the vehicle If the condensed water on the surface of the evaporator does begin to freeze then it could lead to reduc...

Страница 39: ...lines in the A C circuit are rigid Depending on the type of connection there may be a special procedure or a special tool required L1005_026 1 Male side block 3 Pliers to hold the female side 2 Femal...

Страница 40: ...system is either too low or too high it can cause damage to the rest of the system For example when the pressure is too low there will be less refrigerant delivered to the compressor Because the comp...

Страница 41: ...pressor pulley to the compressor drive shaft When electrical current flows through the field coil a magnetic force is created which pulls the drive plate against the rotating compressor pulley Consequ...

Страница 42: ...example under certain operating conditions such as high engine load high coolant temperature or high engine speed the PCM will not turn the compressor on The magnetic clutch is equipped with a therma...

Страница 43: ...er from those found in the A C system with expansion valve Parts Location L1005_030 1 Compressor 6 High pressure service valve 2 Condenser 7 Rigid refrigerant lines 3 Fixed orifice 8 A C cycling switc...

Страница 44: ...sor functions similar to the standard swash plate compressor described earlier The two major differences are the variable swash plate and the control valve The control valve controls the pressure on t...

Страница 45: ...ce can be located a bit further away from the evaporator On the Tribute the flow rate of the refrigerant through the fixed orifice is determined by the cycling of the compressor On the Mazda2 and Mazd...

Страница 46: ...A C System Basic Climate Control The tools shown below are required to service the fixed orifice L1005_047 1 Removal and installation tool 2 Damaged orifice removal tool 03 26 Curriculum Training...

Страница 47: ...er certain operating conditions allow liquid refrigerant to exit the evaporator Because of this the accumulator drier also functions as a second evaporator to ensure that no liquid refrigerant is pass...

Страница 48: ...quired to determine the amount of compressor oil to be added to the new accumulator drier such as draining the compressor oil from the old accumulator drier Control A C Cycling Switch The A C cycling...

Страница 49: ...medium and a high pressure switch The medium pressure switch outputs a cooling fan control signal to the PCM depending on the condenser load The high pressure switch is connected in series to the A C...

Страница 50: ...A C System Basic Climate Control Wiring Diagram L1005_048 1 PCM 4 A C cycling switch 2 A C relay 5 High pressure switch 3 Magnetic clutch 6 Medium pressure switch 03 30 Curriculum Training...

Страница 51: ...type Mazda3 Diesel x Variable displacement Swash Plate Multiflow Mazda5 x Vane rotary Multiflow sub cooling type Mazda6 x Vane rotary Multiflow sub cooling type x MPV LW x Scroll Multiflow sub cooling...

Страница 52: ...A C System Basic Climate Control Notes 03 32 Curriculum Training...

Страница 53: ...assenger compartment which gives the heat up to the incoming air The coolant circulates in two circuits the small and the big circuit In the small circuit the water pump circulates the coolant past th...

Страница 54: ...lly the opposite function of the evaporator The hot coolant flowing through the tubes of the heater core releases its heat to the air passing through the fins of the heater core The fins which are bra...

Страница 55: ...C is activated the pressure on the high pressure side will increase and the pressure on the low pressure side will settle to its operating condition Until this occurs there can be no cooling effect e...

Страница 56: ...perating see the workshop manual for the vehicle specific procedure The measurements are then compared to values in a graph such as the sample graph shown below L1005_055 Excerpt from Mazda3 Workshop...

Страница 57: ...5 bar High pressure side 2 3 MPa 23 bar Air in system Low pressure side 0 05 MPa 0 5 bar to 1 5 MPa 15 bar High pressure side 0 7 MPa 7 bar to 1 5 MPa 15 bar Moisture in system Low pressure side 0 075...

Страница 58: ...and where leak checking plays a very unimportant role The normal seepage of an automotive A C system cannot be stopped and these minuscule leaks should not be taken into consideration during leak tes...

Страница 59: ...ic value COLP should read ON In addition the user can actively send an output signal to the A C relay to check the integrity of the control circuit To do this the PID ACCS must be activated using the...

Страница 60: ...pump to draw the refrigerant out During this process the machine will either manually or automatically weigh the amount of refrigerant taken from the system This is the only 100 reliable way of verify...

Страница 61: ...erant from the system Was approximately the correct amount of refrigerant drained No Follow the Workshop manual procedures to find and repair the leak Yes Evacuate the system using a deep vacuum Does...

Страница 62: ...p manual will give an amount of oil that should be added This ensures proper lubrication of the compressor NOTE When lubricating the O rings with compressor oil use a lint free cloth to apply the oil...

Страница 63: ...fected components must be replaced Failure to do so may result in the new compressor being damaged again NOTE On an A C system with a fixed orifice the accumulator drier can be especially succeptible...

Страница 64: ...much ethylene glycol reduces the heat capacity of the coolant and hence the heating performance of the heater core See the service literature for the correct mixture Thermostat If the thermostat is s...

Страница 65: ...iations A C Air Conditioning HVAC Heating Ventilation Air Conditioning OSC Output State Control PAG Poly Alkaline Glycol PCM Powertrain Control Module PID Parameter Identification WDS Worldwide Diagno...

Страница 66: ...List of Abbreviations Basic Climate Control Notes 06 2 Curriculum Training...

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