Air Conditioning (A/C) System is designed to cycle a/c compressor on and off to maintain preferred temperature and prevent evaporator from freezing. A/C compressor clutch is controlled by low and high pressure cut-off switch. It also has a relief valve to protect air conditioning system from excessive pressure.
Air Conditioning control panel has three knobs: temperature control, blower control and mode knobs.
The auxiliary air conditioning and heater units are separate. The auxiliary A/C unit functions in combination with main A/C system. The heater unit operates independently from main A/C system.
Vehicles with rear air conditioning system have more parts (i.e. rear evaporator coil, expansion valve, blower motor and automatic control system). These vehicles have front auxiliary HVAC control module located above instrument panel and a separate control module usually located overhead, behind front seats.
The most common components for air conditioning system are:
A/C Compressor - the compressor is a belt driven pump that is fastened to the engine. It is responsible for compressing and transferring refrigerant gas.
Condenser - radiates heat; usually located in front of the radiator, but in some cases location may differ. Condensers must have good air flow anytime the system is in operation.
Evaporator - serves as the heat absorption component. It provides several functions. Its primary duty is to remove heat from the inside of your vehicle. A secondary benefit is dehumidification. During humidity, you may see water dripping from the bottom of your vehicle, which is perfectly normal.
Orfice Tube - located in the inlet tube of the evaporator, or in the liquid line; approximately three inches in length and consist of a small brass tube, surrounded by plastic, and covered with a filter screen at each end. It is not uncommon for these tubes to become clogged with small debris.
Thermal Expansion Valve (TXV) - sense both temperature and pressure, and is very efficient at regulating refrigerant flow to the evaporator. They can get clogged with debris and have a corrosion, which will cause malfunction.
Receiver-Drier – function is to separate gas and liquid and to remove moisture and filter out dirt.
Other components of Air Conditioning System that will cause operation problem:
A/C Compressor Drive Belt
Air Condition Hose
Compressor Clutch Cycling Switch
Compressor Drive Pulley
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Compressor Shaft Seal
Compressor Drive Bearing
Manifold and Tube Assembly
Pressure Relief Valve
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Other components of Heating and Ventilation Sytem:
Blower Motor
Blower Motor Resistor
Blower Motor Switch
Heater Core
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Heater Hoses
HVAC Control Assembly
Mode Door Actuator
Water Valve
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