Specifications

Evaporator

A/C System Components

The action between the expansion valve and the evaporator is the key to

heat transfer in the system. The evaporator is the heat exchanger for the

ow-pressure side of the system. It is the key heat exchanger in the A/C

system. All incoming or recirculated air passes through the evaporator. In

doing so, the evaporator absorbs heat from the cabin air (car interior) or

incoming fresh air so this heat can be carried to the

condenser.

Evaporators are typically multiple-flow designs and made from aluminum.

Since the surface fins or plates of the evaporator are usually colder than

the air flowing past them, any moisture (water vapor) in the air tends to

condense and form liquid droplets on the fins. The moisture eventually

drains from the evaporator case through a drain hose to the ground. This

process is called dehumidification.

This process of dehumidifying is not only important to passenger

comfort, but can also be used in cold or humid climates to reduce

windshield fogging. However, a large amount of heat must be removed

from water vapor in order to condense it, so extreme humidity reduces

the

ability of the evaporator to lower the temperature of the incoming air.

3-3

TOYOTA Air Conditioning and Climate Control – Course 752

Evaporator

• Removes heat from

interior as refrigerant is

released into the core.

• Dehumidifies air by con-

densing moisture on the

fins.

Fig. 3-4

752f304

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