WD Catalog 2018

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Glossary
i-2 - -
charge — term used to describe what happens
when refrigerant is added to an air conditioning
system
charging hose — a hose connected to a port on a
manifold gauge set, used to conduct refrigerant
into the AC system from the refrigerant source
chlorofluorocarbon (CFC) — a family of chemi-
cals which includes R-12 and other chemicals. Us-
age is being phased out under federal law.
clutch — a mechanical device which serves to take
the torque in a driving force and transfer it to
another force to be driven — used to drive the
compressor or engine fan
clutch cycling switch — an electrical switch
used to turn the compressor clutch on or off accord-
ing to temperature or pressure demands (one ex-
ample is the thermostat)
compressor — the pump (often referred to as the
heart) of an air conditioning system which pumps
refrigerant through the system and raises the va-
por pressure of refrigerant
compressor head pressure — the pressure of
refrigerant as it leaves the compressor through the
discharge port
compressor shaft seal — a seal located on the
output end of the compressor shaft which serves to
keep refrigerant oil and refrigerant inside the sys-
tem
condensate — the water that collects on surfaces
like the evaporator fins and other cold surfaces
when the air conditioning system is operating
condensation — the process by which gas or va-
por changes to a liquid
condenser — a finned tube device (heat ex-
changer) in which refrigerant loses heat and
changes from hot vapor (or gas) to a warm liquid in
the system
conduction — the ability of a substance to convey
heat from one point to another within the sub-
stance (heat movement in refrigerant)
contaminant — any foreign substance (particu-
larly moisture, dirt or air) which enters an air
conditioner system and must be removed
convection — transmitting or moving heat within
a liquid or gas by moving the heated parts
cutoff switch — a switch on the compressor which
cuts the compressor out of the system when full
throttle is applied to the engine
cycling clutch orifice tube (CCOT) system — a
Frigidaire AC system that uses an expansion tube
(fixed orifice tube) and an accumulator in place of
the expansion valve and receiver-drier
cycling clutch system — a temperature control
system which monitors the operation of the com-
pressor clutch
dehumidify — to remove moisture (humidity)
from the air in the cab or defog the windshield
density — the ratio of mass to it’s volume
desiccant — an agent used in an air conditioning
system to dry or remove moisture by absorption;
found in the receiver-drier or accumulator
desiccant bag — the container found inside some
receiver-driers and accumulators for the desiccant
diaphragm — a device which acts as a bellows or
piston to divide the chambers of a control device
dichlorodifluoromethane — the chemical name
for Refrigerant R-12
discharge — in an air conditioning system, refers
to bleeding or releasing all refrigerant in a system
discharge line — line carrying refrigerant from
the compressor outlet to the condenser inlet con-
nection
discharge pressure — the high side pressure (re-
frigerant vapor) leaving the compressor
discharge switch (compressor) — switch on the
compressor which turns the compressor off when
low pressure of refrigerant is sensed
discharge valve — same as high side service
valve
drain tube — in an AC system a tube positioned to
drain condensation out of the vehicle