A liquid line filter-drier should be placed?
between the condenser and the merering device
The first function a condenser must perform is to _____ the refrigerant before condensing can occur
De-superheat
A parially clogged capillary tube can cause
High Head Pressure
Moisture in a refrigeration system can cause
Oil breakdown,corrosion,acid formation, ALL OF THE ABOVE
Which of the following statement about an evaportator is Not true
It is not affected by dirt or frost build-up
In a direct expansion (DX) evaporator system, the refrigerant enters the evaporator as
a mixture of liquid with some "flash-gases
To process refrigerant to a level equal to a new product specifications as determined by chemical analysis is the definition of
refrigerant reclaiming
A decrease in superheat causes the thermostatic expansion valve
close
In an air condition system that usses a thermostatice expansion valve, the temperature of the evaporator outlet will usually be
warmer than the evaporator inlet
when using an electroni leak detector , the sense probe
should be moved at approximately 1 in per second
In the evaporator
latent heat is transferred from the refrigerated space to the refrigerant
which of the following is not true of a capillary -tube metering device
they are not sensitive to system debris
the oil pressure safety switch is operated by
the sum of suctin pressure and oil pressure
pressure lower than atomospheric are measured in
inches of mercury (hg) or microns
the heat removed from the refrigerant by the condenser is
both sensible and latent heat
what does A/C stand for in HVAC
air conditioning
a low-side float metering device is used
on a flooded evaporator
which of the following will cause a change in compressor capacity
discharge pressure refrigerant vapor density suction pressure ALL OF THE ABOVE
Heat which causes a change in state of material without a change in temperature is called
Latent Heat
heat can travel by
conduction convection radiation
Standard unit for measuring the quantity of heat in a substance is
degrees Farenheit
the temperature at which moisture will start to condense from the air is called
dew point temperature
which of the following is not a themodynamic property of refrigerants?
critical point
heat which causes a change in temperature of a substance is called
Sensible Heat
The main function of the condenser is to
remove heat from the refrigerant
pressures lower than atmospheric are measured in
inches of mercury or microns
a decrease in evaporator pressure causes the automatic expansion valce to
open
the automatic expansion valve is designed to maintain
constant exaporator pressure
3.415 btu's =
1 watt
3,415 btu's
1KW
12,000 BTU =
1 ton
A/C's need at least _____ cfm of indoor air flow per ton of capacity
400
Sub- cooling should be ______ degrees
8-13
central A/Cs should have a temperature drop of 16-20 degrees
16-20
superheat is the differnce between the
saturation temperature of the blue gauge and the physical temperature of the suction line
Lack of air-flow to condenser pressure goes
UP
Lack of air-flow to the evaporator pressure goes
DOWN
Metering device ________ pressure
LOWERS
pressure should be the ______ if unit has been off for awhile
SAME
add ______ to psig to get psia
14.7
compressor pushes out ___ to ____
3 to 1
HFC blends must be charge as a
liquid
Superheat to high ____ refrigerant to low ____
ADD , Take Out
Subcooling to high ____ refrigerant to low ____
Remove, Add