A/C Fundamentals 403a Flashcards
What is heat?
energy
What is the formula to calculate superheat?
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.
Heat intensity is measured by:
temperature
Heat quantity is measured by:
Btu
Heat energy moves from:
hot to cold substances
Latent heat refers to:
the heat energy that must be added or removed to make a substance change state but not temperature.
When a substance changes state from a liquid to a vapour:
heat is absorbed.
When a substance changes state from a vapour to a liquid:
heat is given off.
R-134a refrigerant, when held at a gauge pressure of 1.9 psi, turns into a vapour at a temperature of:
–10F (–23.3C)
To store refrigerant as a liquid at room temperature, it must be:
kept under pressure
As the temperature of a confined refrigerant increases, so does its pressure.
T/F
true
Hydrocarbon refrigerants (HCs) such as propane and butane differ from other air conditioning refrigerants because:
they are flammable
Why should refrigerant oils, air conditioning hoses, air conditioning fittings and receiver/dryers/accumulators be sealed when stored?
(3)
- prevent moisture from contaminating them.
- exclude all possibility of dust and dirt entering them.
- prevent air from contaminating them.
The function of the compressor is to:
circulate the refrigerant
The refrigerant enters the operating compressor as:
low-pressure vapour
The function of the condenser is to:
cool the incoming vaporized refrigerant
Refrigerant leaves the condenser as a:
high-pressure liquid
The receiver/dryer or accumulator removes moisture from the refrigerant by:
using a desiccant material
If a cycling clutch air conditioning system that uses a thermal expansion valve has a sight glass installed, where would it be located?
Between the receiver/dryer outlet and the thermal expansion valve inlet.
The thermal expansion valve controls the:
flow of refrigerant into the evaporator
The thermal expansion valve senses the refrigerant temperature at the:
evaporator outlet
When the thermal expansion valve’s temperature-sensing bulb senses a decrease in temperature, the thermal expansion valve orifice:
decreases the flow of refrigerant
The basic function of an orifice tube, as installed in a cycling clutch orifice tube system, is to:
meter a continuous flow of refrigerant to the evaporator coil
The evaporator:
heats the refrigerant
Which component is always located on the high-pressure side of an air conditioning system circuit?
condenser
Which component is always located on the low-pressure side of an air conditioning system circuit?
evaporator
A pressure-sensitive switch that controls the compressor clutch is used on some air conditioning systems that are equipped with:
an accumulator and an orifice tube
Two (2) styles of fittings used in air conditioning systems are _________________
and ______________________.
flare and O-ring
During the compression strokes the refrigerant _________________ are forced
out of the compressor through one-way _____________________ and a
high-pressure __________________ hose to the condenser.
vapours, reed valves, discharge
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.
vapours, suction, reed valves
The production of R-12 ceased in the mid-1990s due to the concern for damage
caused to the Earth’s protective __________________ layer.
ozone
The three (3) methods by which heat energy moves are \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_, \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ and \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.
conduction, convection and radiation.
The four (4) events in an air conditioning system are:
- expansion
- evaporation
- compression
- condensation
A lubricant that can be used to top up air conditioning system lubricant level is
__________________________ lubricant.
polyol ester (POE)
Subcooling is a term that is used in air conditioning systems when dealing with
refrigerant __________________________.
liquids
Superheat is a term that is used in air conditioning systems when dealing with
refrigerant ______________________.
vapours
The sight glass in the air conditioning system may include a __________________
indicator.
moisture
Air blower fans are used to push or pull air through the ______________ of air
conditioning condensers and evaporators.
fins
Refrigerant hose contains an _________________________ on the inside of the hose
to prevent refrigerant leakage to the atmosphere.
inner barrier layer
