WD Catalog 2018

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4-9 - -
COMPRESSOR
CLUTCH COIL LEAD
WIRE TO EVAPORATOR
THERMOSTATIC
SWITCH
CLUTCH
Note: In some systems (primarily GM systems) the clutch
remains engaged to drive the compressor continuously
during normal operation of the air conditioner. System
pressure and refrigerant flow are controlled using suc-
tion throttling or POA valves at the outlet of the evapo-
rator.
Condensers
Condensers transfer heat energy to the outside air. Condensers may be
mounted on the roof, or behind the grill on the front of the radiator, or may
replace the grill. There are many shapes and sizes to accommodate AC system
design requirements. They include:
1. Radiator Mounted
a. Serpentine
b. Parallel Flow
c. Tube & Fin
2. Remote Mounted
Radiator-mounted condenser construction, currently in use, is as follows:
a. Tube and fin construction is characterized by the use of round
tubes inserted through fin material and then expanded. Hairpin
tubes are used to complete the circuit. This is the strongest type of
construction.
b. Serpentine construction uses single, flat tubing containing mul-
tiple passages that snake from the top to the bottom of the core.
Fins are either the Skyve-type or brazed-ribbon. Serpentine con-
densers are 3/4 to 2 inches thick and exhibit high heat rejection in
a compact size. The pressure drop through the core is most often
greater when compared to tube and fin construction.
c. Parallel-flow condensers are highly efficient, using brazed-ribbon
fins. This is the most efficient type of construction, but is not as
strong as either tube and fin or serpentine. There is also a greater
pressure drop through the core than the tube and fin style.
Condensers
Figure 4-6
A clutch is shown in this
illustration. Typically, a
thermostat in the evapora-
tor acts as a switch and
directs electrical current to
the clutch coil. When the
coil is energized the drive
pulley turns the compressor
shaft.