AC Flashcards Preview

AC Refrigeration > AC > Flashcards

Flashcards in AC Deck (40)
Loading flashcards...
1

The pressure at which the refrigerant changes state from a vapor to liquid

Condensing pressure

2

The pressure at which the refrigerant changes state from a liquid to vapor

Evaporating pressure

3

T/F Superheat always refers to a vapor.

T

4

T/F All liquid must be vaporized for superheating to occur

T

5

Subcooling always refers to a liquid at a temperature _____ its saturation temperature for a given pressure.

Below

6

One main function of a compressor

Circulate refrigerant

7

One function of discharge line

Carry high pressure superheated vapor from compressor discharge valve to condenser

8

Receiver acts as a ____.

Surge tank

9

T/F Liquid line transfers low pressure subcooled liquid to metering device.

F high pressure

10

Meters liquid refrigerant from liquid line to evaporator

Metering device

11

The metering device is a restriction that separates high pressure side from _____ _____ _____ in refrigerant system.

Low pressure side

12

The evaporator, like the condenser, acts as a _____ _____.

Heat exchanger

13

_____ transports low pressure superheated vapor from evaporator to compressor.

Suction line

14

4 stages of refrigeration cycle

Expansion
Evaporation
Compression
Condensation

15

Superheat on the systems low side can be divided into 2 types:

Evaporator superheat
Total (compressor) superheat

16

What controls evaporator superheat?

TXV

17

Low evaporator loads can be caused by 4 things:

Iced up or dirty coil

Defrost circuit malfunction causing coil icing

End of refrigeration cycle

Low refrigerant charge

18

When liquid refrigerant enters the compressor crankcase while compressor is running is called _____.

Flooding

19

Name 2 things could cause slugging to occur?

Bad TXV

Low load

20

3 metering devices

Thermostatic expansion valve (TXV)
Automatic expansion valve (AXV)
Capillary tube

21

If the diameter is too small _____,

the evaporator will be starved.

22

If a capillary tube is over/under charged, it will backup the excess liquid in the condenser causing high/low head pressure.

Over
High

23

It is extremely important to install a filter drier before the capillary tube to catch any _____ _____.

Foreign objects

24

3 main functions of TXV

Provide constant amount of evaporator superheat

Keep evaporator full of refrigerant

Prevents flood back of refrigerant to compressor

25

Color codes

R11
R12
R134A

Blue
Yellow
Blue

26

Air may enter refrigeration system because of what 3 things?

Tube, gasket or flange leaks

Poor charging procedures

Poor recovery or recycling procedures

27

2 types of leak detection

Electronic
Ultraviolet (UV) Fluorescent

28

What 2 things are detrimental to a refrigeration system?

Air
Moisture

29

New and replacement compressors come shipped with dry nitrogen that needs to be removed and _____ prior to use.

Evacuated

30

If the contamination from a burned out and or sludged compressor reaches a replacement compressor, the new compressor will probably _____.

Burn out