WD Catalog 2018

4-7

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Compressor Output (Efficiency)

The Zexel compressor has design improvements for easy seal replace-

ment. The General Motors (Harrison) DA-6 is a downsized, lightweight

version of earlier GMA-6 six cylinder axial compressors. The DA-6 is easy

to service or repair, and has all metric dimensions. It looks different than

the old A-6 but works the same way internally. Components have smaller

dimensions so parts are not interchangeable with the A-6.

5. Wankel Compressor

The Wankel Rotary compressor, has a figure eight-shaped cavity in the

compressor center housing. A triangular rotor is driven by gears from the

compressor drive shaft. As the rotor turns, a low pressure (suction) is

formed at the suction ports and a high pressure is built up at the dis-

charge ports. The suction and discharge ports are located on the compres-

sor end plate, along with the two service ports. There is no suction valve,

only a discharge valve.

Compressor Output (Efficiency)

Engine speed has an effect on the output of all compressors. The two charts in

Figure 4-5 show typical compressor output variations. The column of numbers

on the left of each chart represent BTU’s per hour (x1000) based on the

compressor speeds (RPM) shown across the bottom. As you can see, the faster

the engine turns the compressor shaft, the greater the output. Note how

rapidly output is increased by operating speed of the compressor, and the effect

suction pressure (operating conditions) can have on compressor output. Actual

operating conditions will affect these performance curves.

Note:

Larger capacity compressors like the Climate Control

Inc. 210 and Sanden model 510, are frequently speci-

fied for heavy duty vehicle applications. Larger ca-

pacity compressors are very important when a sepa-

rate bunk AC unit is part of the system.