Deck 29: Troubleshooting and Typical Operating Conditions for Commercial Refrigeration

Question 1

With the entering air to the condenser above 70 ° F, the temperature difference between the outdoor air and the condensing temperature on standard units will be ____.

A) 10 ° F to 15 ° F
B) 15 ° F to 20 ° F
C) 20 ° F to 25 ° F
D) 25 ° F to 30 ° F

Answer 1

D

Question 2

In a high-temperature refrigeration unit, the boiling point of the refrigerant in the coil is normally ____ lower than the cabinet temperature.

A) 5°F to 15°F
B) 10°F to 20°F
C) 25°F to 35°F
D) 35°F to 46°F

Answer 2

B

Question 3

The process of ice making usually occurs in which temperature range?

A) -10°F to 0°F
B) 0°F to 5°F
C) 5°F to 20°F
D) 20°F to 30°F

Answer 3

C

Question 4

In a wastewater system, the water entering the condenser is 85°F and the water leaving the condenser is 105°F. Which of the following statements is a logical explanation for the above conditions?

A) reduced water flow through the condenser
B) scale buildup in the water circuit
C) excess water flow through the condenser
D) both a and b

Question 5

An air-cooled R-12 refrigeration system is operating normally with a suction pressure of 25 psig and a head pressure of 136 psig. Which of the following represents a possible set of operating pressures if the condenser fan motor burns out?

A) high side 136 psig, low side 25 psig
B) high side 100 psig, low side 15 psig
C) high side 200 psig, low side 20 psig
D) high side 180 psig, low side 35 psig

Question 6

Bubbles in the sight glass always indicate refrigerant shortage.

Question 7

Dirty condenser coils are often the cause for inefficient condensers.

Question 8

In a water-cooled condensing unit/cooling tower combination, the temperature difference of the water through the condenser will be approximately ____.

A) 10°F
B) 20°F
C) 30°F
D) 40°F

Question 9

In a wastewater cooled system, the difference between the condensing temperature of the refrigerant and the leaving water temperature is approximately ____.

A) 10°F
B) 20°F
C) 30°F
D) 40°F

Question 10

Since many new replacement refrigerants are being used throughout the industry, a technician should rely on system temperatures to ease the troubleshooting process.

Question 11

Because of the low refrigerant flow rate through the compressor and the system being undercharged, the 100% saturated vapor point in the condenser will be very low in the condenser, causing low condenser subcooling.

Question 12

A sight glass that is full of vapor or liquid may look the same.

Question 13

The refrigerated cabinet temperature of a high-temperature refrigeration unit ranges from ____.

A) 25°F to 45°F
B) 45°F to 60°F
C) 60°F to 75°F
D) 75°F to 95°F

Question 14

High compression ratios will lead to lower compressor discharge temperatures.

Question 15

A thermostatic expansion valve's capacity will drop if the pressure drop across the valve increases.

Question 16

Low density vapors entering the compressor will mean low refrigerant flow through the compressor.

Question 17

Medium-temperature refrigerated cabinet temperatures range from ____.

A) 5°F to 20°F
B) 20°F to 35°F
C) 30°F to 45°F
D) 35°F to 50°F

Question 18

Condensing units located outside that are required to operate year-round must have ____.

A) larger fan motors
B) CPR valves
C) all weather protection
D) head pressure control

Question 19

The approach of a cooling tower is the ____.

A) difference between the entering and leaving wet-bulb temperatures
B) number of degrees the water is cooled in the tower
C) difference in temperature between the entering air wet-bulb temperature and the sump water temperature
D) difference in temperature between the entering air web-bulb temperature and the water entering the tower

Question 20

In a wastewater system, the water entering the condenser is 85°F and the water leaving the condenser is 90°F. Which of the following statements is a logical explanation for the above conditions?

A) reduced water flow through the condenser
B) water regulating valve stuck in the wide-open position
C) excess water flow through the condenser
D) both b and c

Question 21

Most water-cooling towers can cool the water that supplies the condenser to a temperature within ____________________°F of the wet-bulb temperature of the ambient air.

Question 22

In a 2-ton capillary tube system, the unit does not develop full capacity. Head pressure is low and suction pressure is high. What is the problem?

Question 23

In a 2-ton capillary tube system, the unit does not develop full capacity. Head pressure is high, suction pressure is high, and there is no superheat. What is the problem?

Question 24

In a 2-ton capillary tube system, the unit does not develop full capacity. Head pressure is low and suction pressure is low. What is the problem?

Question 25

Why is it that many products that require medium-temperature refrigeration will not freeze at 30°F?

Question 26

In a 2-ton TX valve system, the unit does not develop full capacity. Head pressure is high, suction pressure is slightly above normal, superheat is normal, and subcooling is above normal. What is the problem?

Question 27

In a 2-ton TX valve system, the unit does not develop full capacity. Head pressure is high, suction pressure is slightly above normal, and subcooling is below normal. What is the problem?

Question 28

For each 12,000 Btu/h capacity, a wastewater-cooled condensing unit uses approximately ____________________ GPM.

Question 29

If a system has a(n) ___ for a metering device, the device will try to maintain evaporator superheat even with an excessive overcharge.

Question 30

Will the gauge readings be high or low with a system using a capillary tube that has a low refrigerant charge?

Question 31

For each 12,000 Btu/h capacity, a water-cooled condensing unit and cooling tower combination will circulate approximately ____________________ GPM through the condenser.

Question 32

The water quality required to maintain the water level in the sump is called ____________________.

Question 33

A low refrigerant charge will cause a(n) ____________________ suction pressure, which will increase the compression ratio.

Question 34

If the evaporator and compressor are starved of refrigerant, the condenser will also be starved.