The R-134a air conditioning system is an expansion valve system. Heat is transferred from the hot cab air to the cold refrigerant in the evaporator. The refrigerant is then transported to the condenser. Heat is deposited outside the condenser.
In the heating system, heat is transferred from the hot engine coolant to the cold cab air in the heater coil. The engine coolant is then transported to the engine. When the coolant is back in the engine, the coolant is heated again.
Air Conditioner Instruction Plate Information and Location
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| Illustration 1 | g03649622 |
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Typical example (1) Air conditioner instruction plate | |
Air conditioner instruction plate (1) identifies the system refrigerant as R-134a, lists the system capacity for refrigerant, and identifies the type of refrigerant oil used to lubricate the refrigerant compressor. The air conditioner instruction plate is located inside the left front access door in area (A), shown in Illustration 1. The air conditioner instruction plate for 312E Excavators with a "GAC" serial number prefix is located on the lower left front of the cab, in area (B), shown in Illustration 1.
R-134a Air Conditioning System Service Port Locations
The R-134a service ports used for the R-134a air conditioning system are quick-connect/disconnect style fittings. In an R-134a air conditioning system, the sizes of the service ports differ, with the high-pressure service port being larger than the low-pressure side service port.
The location of the service ports varies based on system layout and machine configuration. Refer to the following examples for typical service port locations.
Location By Refrigerant Compressor
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| Illustration 2 | g03655290 |
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Typical example (E) Refrigerant compressor (2) High-pressure side service port (3) Low-pressure side service port | |
High-pressure side service port (2) and low-pressure side service port (3) are located near refrigerant compressor (C).
Location Below Refrigerant Compressor
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| Illustration 3 | g06018458 |
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View under engine | |
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| Illustration 4 | g06017900 |
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Typical example (E) Refrigerant compressor (2) High-pressure side service port (3) Low-pressure side service port | |
Location By Refrigerant Condensor
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| Illustration 5 | g03655575 |
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Typical example (D) Refrigerant condenser (2) High-pressure side service port (3) Low-pressure side service port | |
High-pressure side service port (2) and low-pressure side service port (3) are located near refrigerant condenser (D).
Ambient air - Outside air
Charge - The charge is a predetermined amount of refrigerant that is put into the air conditioning system by weight.
Compressor - The compressor is a component in the system that increases the pressure of the refrigerant in the system by pumping.
Condenser - The condenser is a component in the system that changes the refrigerant from gas to a liquid.
Contaminants - Dirt, water, and air
Desiccant - The desiccant is part of the receiver or the accumulator that removes the moisture from the air conditioning system.
Detecting - Detecting is finding the source of the problem in the system.
Diaphragm - The diaphragm is a rubber-like material. The diaphragm divides the upper chamber and the lower chamber in the thermostatic expansion valve.
Discharge - The discharge is the removal of some of the refrigerant or the removal of all the refrigerant from the air conditioning system.
Discharge side - The discharge side is the outlet from the compressor to the condenser coil.
Evacuating - Evacuating is the removal of air and moisture from the air conditioning system.
Evaporation - Evaporation is the process of changing a liquid to a vapor.
Evaporator - The evaporator is the component in the air conditioning system that changes the refrigerant from a liquid to a gas by the addition of heat.
Expansion Valve - The expansion valve is a component in the air conditioning system that regulates the flow of liquid refrigerants into the evaporator.
Fluid - Fluid is a liquid or a gas.
Formation of Bubbles - The formation of bubbles in the sight glass of the receiver-dryer indicates that too little refrigerant remains.
Flush - To remove foreign material and oil from the system, flush the system with fluid that is approved. The fluid must be approved by the SAE standard and approved by the ISO standard.
Freeze - Freezing can cause a liquid to become a solid.
Gas - gas is a vapor which contains no liquid.
Graduated Container - A graduated container is a glass scale that is used to measure a fluid in ounces or milliliters.
Heat - Thermal energy
Identifier - The identifier is an instrument for testing the system. The identifier is used for determining the type of refrigerant in the system. The identifier is also used for determining the percent of air in the system.
In-line dryer - A component of the air conditioning system that removes contaminants (moisture) from the system
Latent heat - The quantity of heat needed to cause a change of state between liquid and gas of the refrigerant without changing the temperature of the refrigerant.
Latent heat of condensation - The quantity of heat that is released from a vapor as the vapor is changed into a liquid at a constant temperature.
Latent heat of evaporation - The quantity of heat that is absorbed by a liquid as the liquid is changed from liquid into a vapor at a constant temperature.
Leak detector - The leak detector is a device that is used to locate leaks in the air conditioning system.
Liquid line - The liquid line is the line that connects the condenser coil, the receiver-dryer, and the expansion valve together in an expansion valve system. The liquid line is also the line that connects the condenser coil and the orifice tube together in an orifice tube system.
Magnetic clutch - The magnetic clutch is a device which is used as a coupling. The coupling turns the compressor on and off.
Manifold gauge set - The manifold gauge set is complete with gauges and hoses that are used to measure the pressures in the air conditioning system.
Moisture - Moisture is water in the air or water that is in the refrigerant.
Moisture indicator - The moisture indicator is the device that uses color to display if the material in the dryer is fully soaked with moisture. The moisture indicator will display a pink color if the moisture indicator is soaked with moisture. The moisture indicator will display a blue color if the moisture indicator can absorb more moisture.
Overcharge - Overcharge is having too much refrigerant in the air conditioning system.
Partial charge - A partial charge is less than a full charge of refrigerant put into the air conditioning system.
Performance test - The performance test is the notation of temperatures and pressures under controlled conditions, that determine if the air conditioning system is operating normally.
Refrigerant quick-check procedure - The refrigerant quick-check procedure is a fast check without the use of instruments.
Receiver-dryer - The receiver-dryer is the component in the air conditioning system that removes the contaminants (moisture) from the circuit.
Reclaim - The reclaiming and the restoring of air conditioner refrigerant must meet the SAE specification and the ISO specification. Air conditioner refrigerant can only be reclaimed at a remanufacturing facility.
Recover - Recovering is the removal of the air conditioner refrigerant from the air conditioner system and storing of the refrigerant in an approved container. The removal of the refrigerant can be done without necessarily testing or processing the refrigerant in any way.
Recycle - Usually, the recycling of the refrigerant is completed at the site or at the service shop. The refrigerant can be cleaned by separation of oil. The refrigerant can be cleaned with passes through the filter in the dryer.
Refrigerant - The refrigerant is the fluid that is used in the air conditioning system that removes the heat from the operator compartment.
Refrigerant oil - Refrigerant oil is the oil that is used in the air conditioning system.
Sight glass - A window that allows refrigerant flow to be observed
Stabilize - If the system is constant, the system is stabilized.
Stuck - Sticking will cause the prevention of free movement.
Subcooling - The additional cooling of the refrigerant in the bottom of the condenser after the refrigerant has charged from vapor to a liquid.
Suction side - The suction is the connection that is between the evaporator coil and the compressor.
Superheat - The additional heating of the refrigerant in the bottom of the evaporator after the refrigerant has changed from a liquid to a vapor.
Vapor - Gas