Heating and Air Conditioning: Description and Operation

Air conditioning (A/C) system
The A/C system uses the principals of thermodynamics to cool passenger compartment of vehicle. Using engine power, the compressor compresses gaseous refrigerant into high temperature/high pressure gas. Then it pumps this gas into a condenser unit built onto the vehicle's radiator. The condenser cools gas, changing it into high pressure and low temperature liquid refrigerant. Then the liquid goes to receiver/drier which first removes any liquid water and then sends liquid to an evaporator in blower/evaporator unit inside passenger compartment. The evaporator uses passenger compartment temperature to turn the liquid back into a gas, extracting heat from passenger compartment. The gas is sent back to the compressor, and the cycle begins again.

A/C relay
A/C relay is an electrical switching box that closes the circuit connected with A/CON fuse and compressor clutch. The relay is controlled by the engine control unit (ECU) only. If the engine coolant exceeds a certain temperature, the engine control unit (ECU) sends a signal to trigger A/C relay and to shut off A/C system. At starting or light acceleration, the engine control unit (ECU) sends a signal to trigger A/C relay and to shut off A/C system for five seconds. It is a replaceable item.

Blower
The blower draws in passenger compartment air and sends it through the evaporator coil. It consists of a blower fan and an electric motor.

Blower motor
Blower motor speed is controlled by the blower knob and the resistor assembly in the blower unit. When the blower knob is in the OFF position, the motor ground circuit is open and the blower motor does not operate. When the switch is in the first position, current flow from the blower motor is restricted by the three resistors in the resistor assembly, and the blower motor turns at a low speed. Changing the blower switch to second, third, or fourth positions causes the circuit resistance to decrease and the blower motor speed becomes correspondingly faster.

Compressor assembly
The compressor assembly is the primary moving part of the air conditioning system. If it fails, there is no compression of refrigerant, and no movement of refrigerant through system. It is located on the left side of the engine and is connected to the engine crankshaft by a drive belt. It consists of the compressor, the manifold assembly, the compressor clutch, and the drive pulley.

Compressor clutch
The compressor clutch engages the compressor. It is a magnetic unit operated from air conditioning switch in passenger compartment. It is a serviceable and replaceable item.

Condenser
The condenser is mounted in front of radiator. It consists of a series of coils which cool refrigerant. It is a serviceable and replaceable item.

Condenser fan
The condenser fan improves air flow through the condenser. The condenser will still have a high volume of air flowing through it even if vehicle is standing still. It is powered by an electric motor connected to condenser fan relay. Condenser fan relay is an electrical switching box that closes the circuit connected with condenser fan.

Evaporator assembly
The blower/evaporator assembly houses the blower fan and the blower motor for air conditioner system. It consists of the evaporator core and the expansion valve.

Evaporator core
The evaporator core is an air cooler and a dehumidifier. As refrigerant enters, it boils and absorbing heat from air being blown through the core by heater blower motor. This cools the air, which is directed to passengers through air ducts. As the air is cooled, moisture in air condenses on the core and is drained off. The result is cold and dry air. The evaporator core is a serviceable and replaceable item.

Expansion valve
The expansion valve allows high pressure liquid to expand as it enters evaporator. By allowing liquid to expand, it will absorb more heat in evaporator. Valve also meters amount of refrigerant entering system to prevent evaporator core from flooding.

Fresh/Recirculation actuator
When fresh/recirculation switch in heater and A/C control panel is pushed, motor in fresh/recirculation actuator assembly moves and its position is not fed back to fresh/recirculation switch.
When desired air fresh/recirculation door position is reached, motor stops.

Heater
The dehumidified air is reheated as it passes through the heater core in heater unit. The heater is warmed by the engine coolant passing through the tubes of the heater core. Heat is transferred to the core fins and passed off to the air flowing past fins. The position of the air temperature valve in air conditioning module determines how much of total airflow is permitted to pass through the heater. This determines the warmth of overall air flow that is sent into the passenger compartment.

Hoses and lines
Hoses and lines carry the refrigerant between the major components of A/C system. Lines are made of metal and are rigid. Hoses are made of flexible rubber and are designed for either high or low pressure. They are replaceable items.

Receiver drier
The receiver drier receives liquid refrigerant from the condenser, removes any water in it, and then sends refrigerant to the evaporator. It is a replaceable item.

Service ports
Service ports allow the injection or recovery of refrigerant to the A/C system. High pressure service port is mounted in the high pressure line coming from receiver drier. Low pressure service port is in the section of flexible hose that connects the evaporator return line to the compressor.

A.Q.S(Air quality control system)
A.Q.S sensor is located at center support in front of the engine radiator, and detect hazardous elements in ambient air providing output signal to control. It will detect sulfurous acid gas. carbon dioxide, carbon monoxide, hydrocarbon allergen.

DEF logic
With blower switch ON, A/C system operates automatically and fresh/recirculation door moves to FRE position when turning mode switch to DEF position. If DEF is operated when A.Q.S is activated A.Q.S is canceled for DEF mode and then A.Q.S operates with other mode position.

Refrigerant

Identifying R-134 (R-134a) Systems
In an effort to avoid the use of ozone-depleting CFC refrigerants, Kia Motor Company has introduced a new refrigerant system for this vehicle. This system uses non-CFC-based refrigerant R-134a.
This new type of refrigerant has many of the same properties as R-12 and is similar to R-12 in form and function. R-134a is a hydrofluorocarbon (HFC)-based refrigerant, however, R-12 is a chlorofluorocarbon (CFC). With no chlorine atoms in its molecular structure, use of R-134a refrigerant will not have any harmful effects on the atmosphere's ozone layer.

Identifying R-134a and R-12 A/C Systems
To determine which types of A/C system a particular vehicle has, inspect A/C system's major components and refrigerant lines for special tags. If system has yellow R-134a "NON-CFC" tags, it is an R-134a system and uses R-134a refrigerant. If there are no special R-134a "NON-CFC" tags on A/C system components or lines, the system uses R-12.

CAUTION: Do not add R-12 refrigerant to an A/C system that requires use of R-134a refrigerant. Do not add R-134a refrigerant to an A/C system that requires use of R-12 refrigerant. These two types of refrigerant should never be mixed. Doing so may cause damage to A/C system.

Precaution for new refrigerant (R-134a)

CAUTION: R-12 and R-134a components are not interchangeable. Do not replace components from an R-134a system with components for an R-12 system. Mixing components from these two types of systems may cause component failure and damage to A/C system.




R-134a system components
The major components of R-134a A/C system are similar to those used previously on R-12 systems. R-12 and R134a components are similar in design and function. As a result, all removal and installation procedures outlined for R-12 components can be used for R-134a components.

(Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)