WorksheetsDomestic Refrigeration
Total questions: 24
Worksheet time: 15mins
While carrying out repairs, you notice a split in the cable exposing a live conductor. You should:
wrap insulation tape around the exposed part
leave it alone
tell the client
replace it
Static fin and tube condensers are sometimes called:
forced draft condensers
natural draft condensers
fan cooled condensers
evaporative condensers
To reduce the risk of the domestic finned tube evaporator becoming blocked with ice, the evaporator is designed with:
a close fin spacing
thick plate surface
wide fin spacing
thick heavy duty fins
In a domestic freezer, instead of electric mullion heaters, hot gas lines are often diverted from the compressor to:
increase the cooling effect in the freezer
stop condensation formation around doors
give a quicker defrost in the freezer
increase the off cycle in the refrigerator
Non-condensables such as air cause problems in a domestic refrigeration system. One of these is:
a reduction in the life of the compressor
an increase in head pressure
decontamination of oil in the system
a lower suction pressure and temperature
The most common refrigerant metering device in domestic refrigeration is the:
low side float
T.X valve
suction line accumulator
capillary tube
Systems with capillary tubes used as a metering devices are more suitable for evaporators with a:
heavy load
light load
constant load
fluctuating load
The reason that the accumulator is located at the end of the evaporator is to prevent:
high current draw on start up
oil slugging in the evaporator
flood back
a build up of refrigerant in the condenser
The capillary tube is designed to equal the:
capacity of the condenser
pumping capacity of the compressor
total capacity of the evaporator and the condenser
total capacity of the evaporator and the compressor
The reason a filter drier is installed immediately before the capillary tube is to:
prevent hot gas entering the evaporator
control the amount of refrigerant entering the capillary tube
prevent oil and moisture entering the capillary tube
create a pressure drop to aid the capillary
The suction line accumulator:
builds up pressure and discharges gas to the compressor
collects liquid refrigerant and boils it off
distributes liquid refrigerant throughout the system
meters the refrigerant to control capacity
When the thermostat bulb is strapped to the evaporator it controls the temperature of the:
air space
evaporator
trapped cold air
cabinet
Inside some frost free refrigerators there is a thermostatically controlled baffle plate which:
controls the compressor running time
controls the defrost heaters
controls the amount of air entering the refrigerator cabinet
limits air movement in the freezer cabinet
In a frost-free refrigerator, the effect on the system performance of the timer motor burning out would be
warm food compartment
longer running
little or no air flow
all of the above
When charging a domestic refrigerator to a frost line the frost should extend to:
the inlet tube of the evaporator
the suction line at the inside of the cabinet wall
approximately 400mm before the compressor
90% of the way through the evaporator
On a domestic deep freezer the purpose of the “fast freeze” switch is to:
make the compressor run faster
make the evaporator colder
over-ride the thermostat contacts
over-ride the relay and overload contacts
When replacing a burnt out compressor the system should be:
flushed with R12 prior to fitting the compressor
flushed with R22 prior to fitting to the compressor
fitted with a burnout filter drier
blown out with dry nitrogen
Testing for door seal leakage is usually done using:
an anemometer
a vacustat
a piece of paper
a smoke generator
Due to the nature of the following questions more than one choice may be correct.
Unit: Refrigerator/freezer (Standard single door).
Fault: Food compartment too cold.
door gasket not sealing properly
thermostat control set too warm.
evaporator tray, condition baffle set in wrong position
thermostat sensor bulb come loose or located in wrong location
Due to the nature of the following questions more than one choice may be correct.
Unit: Chest or Upright freezer.
Fault: No freezing. Unit does not run.
relay disconnected from compressor
broken power cord
unit not switched on at a power point
sticking (closed) thermostat contact
Due to the nature of the following questions more than one choice may be correct.
Unit: Refrigerator/freezer (Standard single door fan forced)
Fault: Freezer compartment not cold enough.
restriction in the system
overloaded with non-refrigerated produce
short cycle on the overload
refrigerant shortage
Due to the nature of the following questions more than one choice may be correct.
Unit: Side by side refrigerator.
Fault: Suction line iced back to compressor.
moisture in system
non-condensables in system
blocked evaporator
overcharged system
Due to the nature of the following questions more than one choice may be correct.
Unit: Cyclic defrost refrigerator.
Fault: Runs for long periods of time before cycling.
door gasket not sealing
refrigeration plate or serpentine coil iced up
defrost heater not working
thermostat sensor bulb loose or disconnected
On a domestic compressor, with terminals as shown in the diagram, Which terminal is common?:
A and B=16 ohms. B and C=9 ohms. C and A =25 ohms
A
B
C
not enough information
