Unit 25 review

Two-temperature operation of a refrigeration system is necessary when ____.

• the compressor must be protected from overloading

• more than one evaporator is used with a compressor

• the coil in the evaporator is excessively long

• a multiple-circuit distributor is used

Tags

NGSS.HS-PS3-4

Technician "A" says that a multi-evaporator system equipped with three evaporators (one high temperature, one medium temperature, and one low temperature) will use one evaporator pressure regulator and two flow check valves. Technician "B" says that the crankcase pressure regulator is used to keep the low-temperature compressor from overloading on a hot pulldown. Which of the following statements is correct?

• Technician "A" is correct. Technician "B" is correct.

• Technician "A" is correct. Technician "B" is incorrect.

• Technician "A" is incorrect. Technician "B" is correct.

• Technician "A" is incorrect. Technician "B" is incorrect.

Tags

NGSS.HS-PS3-4

To protect the compressor during periods of hot pull down, a(n) ____ valve is used.

• EPR valve

• CPR valve

• CVPC valve

• PCV valve

The refrigeration compressor motor can be operated at about ____% over its rated capacity without harm during the pulldown.

• 10
• 20

• 2

• 15

Refrigeration systems are designed to operate year round. For this reason they are equipped with ____.

• Low ambient control

• seasonal offset

• Fall evaporator control

• Summer evaporator control

Which of the following is a type of low-ambient temperature head pressure control?

• CPR.

• EPR.

• Fan cycling.

Tags

NGSS.HS-PS3-3

Frequently on smaller condensing units, one fan will run continuously and the other fan will be cycled on and off with a(n) ____.

• switch

• Low ambient control

• thermostst

• archicetect control

Tags

NGSS.MS-PS3-3

____ are snap-acting valves that open and close very fast when the electrical energy is applied to the coil.

• Contactors
• solenoid valves

• EPR valves

• Head masters

Tags

NGSS.HS-PS3-3

When a system pumps down, where is the refrigerant stored?

• Condenser and receiver.

• Evaporator and compressor.

• Condenser and compressor.

• Both a and c.

Random defrost is accomplished ____.

• with a timer
• a thermostat

• pressure control

• nothing

Tags

NGSS.MS-PS3-5