Commercial Refrigeration Certification
Questions and Answers 100% Verified
"Pump down" means to capture system refrigerant in the:
A. recovery cylinder.
B. compressor.
C. condenser and/or liquid receiver.
D. suction accumulator. - ANSWER - C. condenser and/or liquid receiver.
A _____ is usually required for ultra-low temperature applications.
A. cooler
B. comfort cooling system
C. freezer
D. cascade system - ANSWER - D. cascade system
A _____ type metering device is best suited in applications where freeze protection is required.
A. thermostatic expansion valve (TEV)
B. automatic expansion valve (AEV)
C. float
D. capillary tube - ANSWER - B. automatic expansion valve (AEV)
A customer calls and indicates that a walk-in freezer is running gradually higher box
temperature. The technician finds the box at 15°F, the thermostat is set properly for a freezer
application, and the condensing unit is operating, but not cycling after adequate pull down time.
An inspection of the evaporator reveals heavy ice accumulated across the top two rows, and the
entire body of the thermostatic expansion valve and power element frozen in a bell of Ice. The
technician decides to advance the electromechanical defrost timer to the next defrost period and
observe the defrost function. In doing so, the evaporator defrosts to the level of the ice build-up,
but no further. All power to both the freezer and condensing unit is removed, locking and tagging
each disconnect. The technician then defrosts the remainder of the ice from the evaporator and
expansion valve body. All evaporator housings are placed back and sec - ANSWER - B. over a
period of time, moisture had gathered under the flare nut on the evaporator side of the
,expansion valve. Repeated freezing and thawing had created enough force to damage the flare,
creating a slow refrigerant leak.
A defrost cycle is required whenever the evaporator must operate below:
A. 0°F
B. 32°F
C. 10°F
D. 20°F - ANSWER - B. 32°F
A dirty evaporator and subsequent low evaporator pressures will cause:
A. high compression ratios.
B. low compression ratios.
C. high head pressure
D. high suction pressure. - ANSWER - B. low compression ratios.
A customer calls and indicates that he has a walk-in freezer that is cutting on and off after a very
short run time on a repeated basis. He indicates that he had a higher than normal power bill the
previous month and thinks the unit's erratic behavior may have contributed to the higher bill. The
technician arrives and inspects the freezer. The freezer box temperature is —10°F, and the
condensing unit is off. However, the technician observes the condensing unit operate and short
cycle several times within a few minutes of the demand being satisfied. The technician shuts the
unit down, locking and tagging the disconnect.
This system is equipped with both low and high pressure switches, a suction line accumulator,
and a liquid line solenoid. The technician notices that there is ice build-up from the outlet of the
liquid line solenoid to the expansion valve.
Manifold gauges are attached to the service ports. Removing t - ANSWER - C. the liquid line
solenoid is leaking during the off cycle, causing the low pressure switch to cycle the condensing
unit.
A customer complains that their counter top ice machine is making a loud noise and not
producing any ice. Upon arrival, the technician removes the front panel and determines that the
noise is coming from the ice machine auger. Before the technician can unplug the power supply,
the auger drive motor overload opens and the drive motor stops. The machine's compressor
continues to operate.
, The technician unplugs the ice machine and attaches gauges to the low and high side service
ports. In addition, a clamp-on ammeter is placed on the power lead to the compressor. The
technician turns the power switch to the off position and plugs the ice machine back into the
power supply. The technician locates the manual reset switch located on top of the auger drive
motor and attempts to reset the switch. The switch will not reset and the motor frame is very hot.
Using ice from another machine in a heavy plastic bag, the motor is coo - ANSWER - C. the lack
of water flow reduced evaporator load, which resulted in the auger freezing up and the drive
motor tripping the overload. The low pressure and current are the result of low load on the
evaporator. Water flow must be restored and the machine should operate properly.
A customer is experiencing low ice production in a cube type ice machine. Symptoms include
long run cycle, thin or smaller cubes, and low production. The initial visual inspection confirms
the owner's complaint of thin ice and low production. Further inspection reveals that the ice
machine Is equipped with a harvest solenoid and a thermostatic expansion valve. The water
pump is operating and the water reservoir is clean and free of debris. A check of the water
temperature in the reservoir is 32°F. The technician decides to install manifold gauges and
check system pressures. This Indicates slightly elevated suction pressure with the discharge
pressure at or near normal for the application and refrigerant used. A check of evaporator
superheat shows it to be 15°F to 18°F. A check of temperature difference across the harvest
solenoid indicates a temperature rise of approximately 10°F. A check of condenser sub cooling
ind - ANSWER - D. the harvest solenoid ls leaking. keeping the suction pressure above normal,
and
must be replaced.
A customer reports that their low temperature reach-in freezer had a burned compressor
replaced last week by another service company, and now is not cooling properly. When you
arrive and examine the system, you find that the evaporator seems to be starving for refrigerant.
On inspecting the condensing unit, you notice that the liquid line is sweating where it leaves the
filter drier.
This is most likely the result of:
A. debris from the burned compressor has clogged the filter drier.
B. air in the system.
C. low refrigerant charge.
D. refrigerant overcharge. - ANSWER - A. debris from the burned compressor has clogged the
filter drier.
A defrost cycle can be initiated by a:
A. timer.
Questions and Answers 100% Verified
"Pump down" means to capture system refrigerant in the:
A. recovery cylinder.
B. compressor.
C. condenser and/or liquid receiver.
D. suction accumulator. - ANSWER - C. condenser and/or liquid receiver.
A _____ is usually required for ultra-low temperature applications.
A. cooler
B. comfort cooling system
C. freezer
D. cascade system - ANSWER - D. cascade system
A _____ type metering device is best suited in applications where freeze protection is required.
A. thermostatic expansion valve (TEV)
B. automatic expansion valve (AEV)
C. float
D. capillary tube - ANSWER - B. automatic expansion valve (AEV)
A customer calls and indicates that a walk-in freezer is running gradually higher box
temperature. The technician finds the box at 15°F, the thermostat is set properly for a freezer
application, and the condensing unit is operating, but not cycling after adequate pull down time.
An inspection of the evaporator reveals heavy ice accumulated across the top two rows, and the
entire body of the thermostatic expansion valve and power element frozen in a bell of Ice. The
technician decides to advance the electromechanical defrost timer to the next defrost period and
observe the defrost function. In doing so, the evaporator defrosts to the level of the ice build-up,
but no further. All power to both the freezer and condensing unit is removed, locking and tagging
each disconnect. The technician then defrosts the remainder of the ice from the evaporator and
expansion valve body. All evaporator housings are placed back and sec - ANSWER - B. over a
period of time, moisture had gathered under the flare nut on the evaporator side of the
,expansion valve. Repeated freezing and thawing had created enough force to damage the flare,
creating a slow refrigerant leak.
A defrost cycle is required whenever the evaporator must operate below:
A. 0°F
B. 32°F
C. 10°F
D. 20°F - ANSWER - B. 32°F
A dirty evaporator and subsequent low evaporator pressures will cause:
A. high compression ratios.
B. low compression ratios.
C. high head pressure
D. high suction pressure. - ANSWER - B. low compression ratios.
A customer calls and indicates that he has a walk-in freezer that is cutting on and off after a very
short run time on a repeated basis. He indicates that he had a higher than normal power bill the
previous month and thinks the unit's erratic behavior may have contributed to the higher bill. The
technician arrives and inspects the freezer. The freezer box temperature is —10°F, and the
condensing unit is off. However, the technician observes the condensing unit operate and short
cycle several times within a few minutes of the demand being satisfied. The technician shuts the
unit down, locking and tagging the disconnect.
This system is equipped with both low and high pressure switches, a suction line accumulator,
and a liquid line solenoid. The technician notices that there is ice build-up from the outlet of the
liquid line solenoid to the expansion valve.
Manifold gauges are attached to the service ports. Removing t - ANSWER - C. the liquid line
solenoid is leaking during the off cycle, causing the low pressure switch to cycle the condensing
unit.
A customer complains that their counter top ice machine is making a loud noise and not
producing any ice. Upon arrival, the technician removes the front panel and determines that the
noise is coming from the ice machine auger. Before the technician can unplug the power supply,
the auger drive motor overload opens and the drive motor stops. The machine's compressor
continues to operate.
, The technician unplugs the ice machine and attaches gauges to the low and high side service
ports. In addition, a clamp-on ammeter is placed on the power lead to the compressor. The
technician turns the power switch to the off position and plugs the ice machine back into the
power supply. The technician locates the manual reset switch located on top of the auger drive
motor and attempts to reset the switch. The switch will not reset and the motor frame is very hot.
Using ice from another machine in a heavy plastic bag, the motor is coo - ANSWER - C. the lack
of water flow reduced evaporator load, which resulted in the auger freezing up and the drive
motor tripping the overload. The low pressure and current are the result of low load on the
evaporator. Water flow must be restored and the machine should operate properly.
A customer is experiencing low ice production in a cube type ice machine. Symptoms include
long run cycle, thin or smaller cubes, and low production. The initial visual inspection confirms
the owner's complaint of thin ice and low production. Further inspection reveals that the ice
machine Is equipped with a harvest solenoid and a thermostatic expansion valve. The water
pump is operating and the water reservoir is clean and free of debris. A check of the water
temperature in the reservoir is 32°F. The technician decides to install manifold gauges and
check system pressures. This Indicates slightly elevated suction pressure with the discharge
pressure at or near normal for the application and refrigerant used. A check of evaporator
superheat shows it to be 15°F to 18°F. A check of temperature difference across the harvest
solenoid indicates a temperature rise of approximately 10°F. A check of condenser sub cooling
ind - ANSWER - D. the harvest solenoid ls leaking. keeping the suction pressure above normal,
and
must be replaced.
A customer reports that their low temperature reach-in freezer had a burned compressor
replaced last week by another service company, and now is not cooling properly. When you
arrive and examine the system, you find that the evaporator seems to be starving for refrigerant.
On inspecting the condensing unit, you notice that the liquid line is sweating where it leaves the
filter drier.
This is most likely the result of:
A. debris from the burned compressor has clogged the filter drier.
B. air in the system.
C. low refrigerant charge.
D. refrigerant overcharge. - ANSWER - A. debris from the burned compressor has clogged the
filter drier.
A defrost cycle can be initiated by a:
A. timer.
