HVAC 2342 #3

In a commercial refrigeration system using a low pressure control as a motor cycling control, the refrigerant evaporating temperature will be _____ºF lower than the box temperature of the refrigerated space.

15

The cut-out setting for a high pressure control is usually set at _______ above the system's normal high side operating pressure.

20%

As a rule of thumb, the condensing temperature of the refrigerant is ____ higher than the temperature of the air entering the condenser.

35 degrees

A technician is troubleshooting a commercial refrigeration system. The system has higher than normal head pressure and higher thqan normal compressor current. The most probable cause for this is:

Dirty or clogged condenser coil

The Ozone Depletion Potential (ODP) is lowest in _____ type refrigerants.

HFC

The King valve is located between the _____ and the ________.

Liquid receiver/liquid line

A restriction of the air flow over the evaporator would cause:

None of the above

When a filter drier is saturated it will:

Not absorb any additional moisture

What component is not found on the LOW pressure side of a refrigeration system?

Oil separator

Which of the following is not a cause of bubbles in the sight glass?

TEV is flooding the evaporator

In order to prevent condenser noise from traveling along the refrigerant lines the technician should install a:

Vibration absorber

A cold-drink vending machine would normally use:

a capillary tube for the metering device

During the refrigeration cycle, the refrigerant becomes superheated in:

all of the above

Filter drier utilized in commercial refrigeration systems are designed to remove:

all of the above

Liquid refrigerant entering the compressor of a commercial refrigeration system will result in slugging. This can cause:

all of the above

Which of the following may be used to detect leaks in a refrigerant system?

all of the above

One advantage of the capillary tube metering device is:

allows the system pressures to equalize during the off cycle

To compensate for the pressure drop through the evaporator coil, a commercial refrigeration system would use:

an externally equalized TEV

When the technician front seats the commercial service valve he/she is:

closing the valve

A commercial freezer which uses an electric system is in the defrost mode. What statement is correct?

compressor is OFF and evaporator fan is OFF

Crankcase heaters are used to:

control refrigerant migration.

The reduction of air flow across the evaporator causes the temperature of the coil to:

decrease

The TEV sensing bulb should be mounted as close as possible to the exit of the:

evaporator

The technician notices that the suction line is frozen all the way to the input of the compressor, the most probable cause for this condition is:

evaporator fan is not operating

Low superheat is an indication of:

flooded evaporator

Which of the following is an indication that the evaporator is in a starved condition?

high superheat

When using the liquid charging method the unit must be _____and the compressor must be _______.

in a vacuum/turned off

When would the solenoid, used to achieve a pump down cycle in a commercial refrigeration system, be loacted?

in the liquid line

Where would the accumulator in a commercial refrigeration system be located?

in the suction line

If the air flow across the condenseris resticted, the head pressure:

increases

The compressor motor current _______ when the air is reduced across the condenser.

increases

The motor current ________ when the air is reduced across the evaporator.

increases

Which of the following is NOT a cause of high head pressure?

leaking discharge valve in the compressor

The state of refrigerant is different in each component of the refrigerant system. What is the state of the refrigerant in the metering device?

liquid

The TEV is located in the:

liquid line

Which control can be used both as a safety and motor cycling control on commercial refrigeration systems?

low pressure control

Which control energizes the liquid line solenoid in the pump down cycle?

low pressure control

The technician is troubleshooting a system. Both the high side pressure and the low side pressure are low. The most probable cause is:

low refrigerant charge

One symptom of a restricted capillary tube is:

lower than normal suction pressure

Commercial systems use a head pressure controls in order to:

maintain normal head pressure in low ambient temperatures

The function of the Evaporator Pressure Regulator (EPR) is:

maintain the desired temperature in the refrigerated space

During the refrigeration cycle, a change of pressure occurs in the:

metering device

Moisrure in the system can cause ice to form in the:

metering device

The compressor is designed as a vapor pump. When is it permissible to have liquid in the compressor?

never

Which type of evaporator is classified as a non-frosting evaporator?

operating temperatures which do not go much below 32ºF

The contact points on a low pressure control are closed by a:

pressure rise

An accumulator is placed on a commericaal refrigeration system to:

protect the compressor

Which of the following is not a type of defrost system?

pump down cycle defrost

A technician would polace the refrigerant cylinder into a container of warm water in order to:

raise the pressure inside the cylinder.

When a commercial refrigeration system is "short cycling" it is:

rapidly starting and stopping the compressor

A technician is using a special machine to remove the refrigerant from a commercial refrigeration system. This process is called:

recovery

In a commercial refrigeration system, compressor cooling is achieved by:

refrigerant vapors returning to the compressor

When qaq technician is evacuating a system, he or she is:

removing any mositure

A system which uses a TEV requires a compressor that will:

start under a high torque

Which component is not a part of the HIGH pressure side of a refrigeration system?

surge tank

Which control on a commercial system is used as a motor cycling control only?

temperature control

When the Paragon electric defrost timer initiates the defrost cycle:

the compressor is de-energized and the heater is energized.

During the defrost cycle of a commercial system which uses a hot gas defrost system:

the compressor stays running

The technician notices that the temperature on the outlet end of the liquid line drier is cooler than the temperature on the input end. This indicates that:

the drier is clogged or restricted

On a hot gas defrost, what device allows the refrigerant to bypass the condenser?

the hot gas solenoid valve

Which statement describes the Mantitowoc ice machine?

the ice cubes form directly on the evaporator

When performing an evacuation from a capillary tube system, the system should be evacuated from:

the low and high side of the system

A technician is troubleshooting a commercial refrigeration system and observes bubbles in the sight glass. This indicates that:

the system is undercharged

Any pressure that is lower than atmospheric pressure is considered to be:

vacuum

The technician determines that the commercial system is slightly undercharged. He/she would add some refrigerant by using the _____ method.

vapor charging