A/C Fundamentals 403a

Question 1

What is heat?

Answer 1

energy

Question 2

What is the formula to calculate superheat?

Answer 2

SH= T1 - Te
Where:
• SH is superheat,
• Tl is the recorded low pressure gauge reading converted to a temperature and
• Te is the measured evaporator outlet temperature.

Question 3

Heat intensity is measured by:

Answer 3

temperature

Question 4

Heat quantity is measured by:

Answer 4

Btu

Question 5

Heat energy moves from:

Answer 5

hot to cold substances

Question 6

Latent heat refers to:

Answer 6

the heat energy that must be added or removed to make a substance change state but not temperature.

Question 7

When a substance changes state from a liquid to a vapour:

Answer 7

heat is absorbed.

Question 8

When a substance changes state from a vapour to a liquid:

Answer 8

heat is given off.

Question 9

R-134a refrigerant, when held at a gauge pressure of 1.9 psi, turns into a vapour at a temperature of:

Answer 9

–10F (–23.3C)

Question 10

To store refrigerant as a liquid at room temperature, it must be:

Answer 10

kept under pressure

Question 11

As the temperature of a confined refrigerant increases, so does its pressure.
T/F

Answer 11

true

Question 12

Hydrocarbon refrigerants (HCs) such as propane and butane differ from other air conditioning refrigerants because:

Answer 12

they are flammable

Question 13

Why should refrigerant oils, air conditioning hoses, air conditioning fittings and receiver/dryers/accumulators be sealed when stored?
(3)

Answer 13

• prevent moisture from contaminating them.
• exclude all possibility of dust and dirt entering them.
• prevent air from contaminating them.

Question 14

The function of the compressor is to:

Answer 14

circulate the refrigerant

Question 15

The refrigerant enters the operating compressor as:

Answer 15

low-pressure vapour

Question 16

The function of the condenser is to:

Answer 16

cool the incoming vaporized refrigerant

Question 17

Refrigerant leaves the condenser as a:

Answer 17

high-pressure liquid

Question 18

The receiver/dryer or accumulator removes moisture from the refrigerant by:

Answer 18

using a desiccant material

Question 19

If a cycling clutch air conditioning system that uses a thermal expansion valve has a sight glass installed, where would it be located?

Answer 19

Between the receiver/dryer outlet and the thermal expansion valve inlet.

Question 20

The thermal expansion valve controls the:

Answer 20

flow of refrigerant into the evaporator

Question 21

The thermal expansion valve senses the refrigerant temperature at the:

Answer 21

evaporator outlet

Question 22

When the thermal expansion valve’s temperature-sensing bulb senses a decrease in temperature, the thermal expansion valve orifice:

Answer 22

decreases the flow of refrigerant

Question 23

The basic function of an orifice tube, as installed in a cycling clutch orifice tube system, is to:

Answer 23

meter a continuous flow of refrigerant to the evaporator coil

Question 24

The evaporator:

Answer 24

heats the refrigerant

Question 25

Which component is always located on the high-pressure side of an air conditioning system circuit?

Answer 25

condenser

Question 26

Which component is always located on the low-pressure side of an air conditioning system circuit?

Answer 26

evaporator

Question 27

A pressure-sensitive switch that controls the compressor clutch is used on some air conditioning systems that are equipped with:

Answer 27

an accumulator and an orifice tube

Question 28

Two (2) styles of fittings used in air conditioning systems are _________________
and ______________________.

Answer 28

flare and O-ring

Question 29

During the compression strokes the refrigerant _________________ are forced
out of the compressor through one-way _____________________ and a
high-pressure __________________ hose to the condenser.

Answer 29

vapours, reed valves, discharge

Question 30

During the downward stroke of the piston, the compressor pulls the refrigerant
__________________ from the evaporator, through the low-pressure
____________________ hose, through the one-way _____________________
and into the compressor’s cylinders.

Answer 30

vapours, suction, reed valves

Question 31

The production of R-12 ceased in the mid-1990s due to the concern for damage
caused to the Earth’s protective __________________ layer.

Answer 31

ozone

Question 32

The three (3) methods by which heat energy moves are \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_,
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ and \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.

Answer 32

conduction, convection and radiation.

Question 33

The four (4) events in an air conditioning system are:

Answer 33

• expansion
• evaporation
• compression
• condensation

Question 34

A lubricant that can be used to top up air conditioning system lubricant level is
__________________________ lubricant.

Answer 34

polyol ester (POE)

Question 35

Subcooling is a term that is used in air conditioning systems when dealing with
refrigerant __________________________.

Answer 35

liquids

Question 36

Superheat is a term that is used in air conditioning systems when dealing with
refrigerant ______________________.

Answer 36

vapours

Question 37

The sight glass in the air conditioning system may include a __________________
indicator.

Answer 37

moisture

Question 38

Air blower fans are used to push or pull air through the ______________ of air
conditioning condensers and evaporators.

Answer 38

fins

Question 39

Refrigerant hose contains an _________________________ on the inside of the hose
to prevent refrigerant leakage to the atmosphere.

Answer 39

inner barrier layer