Specifications

A/C System Components

An important difference between a compressor and a pump is that a

compressor cannot pump liquids. Since liquids cannot be compressed,

compressor filled with liquid will either lock up or break depending on

the amount of torque applied to its pulley by the engine crankshaft. More

commonly, the reed valve assembly that controls gas flow inside will be

destroyed when a compressor hydraulically locks.

Most compressors have a “bolt-on” fitting block to provide connections to

the low-pressure side of the system (suction side) and high-pressure side

of the system (discharge port). There may also be fittings on or near the

compressor to connect pressure gauges.

Various Toyota vehicles use or have used one of the following types of A/C

compressors:

• Piston

• Through-Vane

• Swash-plate

• Variable Capacity

• Scroll-type

Piston-type compressors have valves to control the flow of intake and

exhaust gases. For simplicity, A/

C compressors use spring-tensioned

stainless steel

reed valves which allow gas flow in one dir

ection and only

when a significant pressure difference exists between the chamber of the

compressor and the intake or outlet passages. The earliest compressors

wer

e belt-driven using two- or three-pistons with connecting

rods and a

3-5

TOYOTA Air Conditioning and Climate Control – Course 752

Reed Valve

Control of

Refrigerant Flow

Reed valves control

both suction and

discharge flow.

Discharge Reed Valve

Suction Reed Valve

Fig. 3-5

752f305

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