WD Catalog 2018

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Glossary
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drier — normally a part of the receiver-drier, used
to absorb moisture in the system using a desiccant
as a drying agent
drive pulley — the pulley that drives the com-
pressor clutch
drying agent — same as desiccant
electronic leak detector — a device designed to
sense leaks in an air conditioning system with ex-
treme accuracy
electronic sight glass — a device using ultra-
sonic principals to sense refrigerant inside an AC
system and provide audible signals when the AC
system has the proper amount of refrigerant
equalizer line — used to control valves in an air
conditioning system to equalize pressure or tem-
perature
ester — a type of lubricant that may be found in R-
134a systems
evacuate — the process of removing all moisture
or air in a system by creating a vacuum in the
system
evaporation — the process by which a liquid
changes it’s state to become a vapor or gas
evaporator — a device with coils and fins through
which liquid refrigerant flows, removing heat en-
ergy from the air, and changing to a vapor
expansion tube — also called a fixed orifice tube
(CCOT system), replaces expansion valve and
meters refrigerant to evaporator
expansion valve — same as thermostatic expan-
sion valve (TXV)
external equalizer — same as equalizer line
Fahrenheit — a scale used to measure tempera-
ture (heat intensity- how hot something is), and
calibrated at 32 degrees Fahrenheit where water
freezes and 212 degrees Fahrenheit where water
boils
fan clutch — a variable speed or on-off clutch
which acts as a coupler (fluid, air or electrical),
between engine and the engine cooling fan
filter — a portion of the receiver-drier used to
remove solid contaminants from the system
flush — the process of removing all foreign matter
from a system by means of pressurized air, refriger-
ant or dry nitrogen
foaming — when observed in the sight glass indi-
cates low level of refrigerant in the system
foot-pound — a measurement of energy required
to raise one pound one foot. In relationship to
torque, it is a force that acts upon a body (such as a
bolt or nut) to produce rotation
freeze-up — the freezing of water or moisture in
the expansion valve orifice or on the fins and coil of
the evaporator
freezing point — the point at which a liquid will
become a solid
Freon® — Dupont registered trade mark name for
refrigerant R-12
front seat — an AC service valve position which
isolates the compressor from the system by closing
the valve (turning the valve stem all the way to the
right)
gauge set — two gauges (sometimes three) in-
stalled on a manifold to test and measure condi-
tions inside the AC system
‘H’ valve — a water valve which returns excess
coolant from the heater inlet back to the engine
cooling system
Halide leak detector — a propane gas device
used to determine the location and severity of an R-
12 leak in the system
head pressure — the pressure of refrigerant from
where it originates at the discharge valve of the
compressor, through all lines and components to
the orifice in the expansion valve
heat energy — heat in action; the movement of a
quantity of heat measured in BTU’s (example, in a
change of state)
heat exchanger — a device which enables fluid at
one temperature (higher) to move heat to another
fluid at a lower temperature