WD Catalog 2018

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Chapter 2 – System Operation
2-4 - -
DOWN UP
INLET OUTLET
PISTON ON
DOWNSTROKE
AND
UPSTROKE
INLET LOW PRESSURE – ON DOWNSTROKE
PISTON SUCKS REFRIGERANT GAS THROUGH
OPEN VALVE
OUTLET HIGH PRESSURE –ON UPSTROKE VALVE
FORCED OPEN AND HOT REFRIGERANT GAS IS
FORCED INTO HIGH SIDE OF SYSTEM
The clutch is mounted on the shaft of the compressor and is engaged by
electromagnetic action. Part of the clutch assembly is an electromagnetic
wire coil. The coil is energized through a thermostat that senses the
temperature in the evaporator coil. If the evaporator is too warm the
electrical contacts close and allows power to flow to the clutch. The
compressor shaft is engaged and moves the refrigerant around inside the
system. Figure 2-4 is a cutaway view of the clutch mounted on the
compressor.
COMPRESSOR
CLUTCH COIL LEAD
WIRE TO EVAPORATOR
THERMOSTATIC
SWITCH
CLUTCH
MAGNETIC
CLUTCH-COIL
REED VALVE
2. Condenser
The refrigerant gas leaves the compressor and moves through a high
pressure hose to the condenser. Inside the condenser the gas “changes
state” and becomes a liquid. It is still hot and under pressure. Remember
in Chapter 1 when we talked about water at 212 degrees Fahrenheit?
Heat energy was involved in the “change of state,” but the temperature
did not change. The same kind of action happens inside the AC system.
The refrigerant gas gives up a lot of heat energy to the outside air as it
“changes state” in the condenser. Figure 2-5 illustrates a condenser. Air
moving through the condenser absorbs heat from the refrigerant. The
amount of air flow through the condenser is the major factor in how well
the condenser functions.
Figure 2-3
The compressor inlet is low
pressure and the outlet is
high pressure. The reed
valves are one way. They
open to allow refrigerant
gas to enter the compressor
on the down stroke and exit
on the upstroke. Note the
open valves in the illustra-
tions.
Figure 2-4
The clutch shown here has
its electromagnetic coil
mounted on the compressor
body. When the coil is ener-
gized, magnetic force pulls
the clutch drive plate into
the pulley. This action locks
the pulley to the compressor
drive shaft and drives the
compressor.