Skill Level:
Mechanic
Mid-Level
Apprentice
A ton of refrigeration is equal to ____________________ BTU/HR?
A compressor is located above the evaporator. What harmful effects could result from over-sizing the suction line on this system?
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3) How do you reverse rotation on a three-phase motor? _______________________________________________________________________________
How is oxidation prevented on the inside of tubing fittings when making high temperature solder joints? ______________________________________________________________________
Give two methods of removing air from a system prior to charging:
A) _____________________________________________________________________
B) _____________________________________________________________________
Liquid refrigerant should be charged into the system only through the: ____________________________________________________________________________
When air conditioning a two-story home, there are two reasons why most of the air should be directed to the second floor when cooling. What are these reasons?
C) _____________________________________________________________________
D) _____________________________________________________________________
The purpose of the thermocouple is to:
E) Stop a furnace from over heating.
F) Turn on fan motors.
G) Control gas pressure.
H) Cut off the main gas valve to the furnace.
What would cause the limit switch to shut cycle on and off?
I) Too much airflow through the furnace.
J) Thermostat heat anticipator not set properly
K) Shorted gas valve.
L) Stopped up air-filter.
If a defrost control doesn’t work in a heat pump the unit will:
M) Blow fuses or trip circuit breakers.
N) Pump down.
O) Cycle on head pressure control.
P) Freeze up the outside coil
Humidifier is controlled from which device?
Q) Thermostat
R) Fan Control
S) Blower Motor
T) Humidistat Sail Switch
Horizontal piping should be run level. True or False?
You are expecting an ammeter reading of only 2 or 3 amps, but your clamp-on meter doesn’t read too accurately below 5 amps. What can you do? _______________________________________________________________________________
Dehumidification in a total comfort system takes place at:
U) Evaporator coil
V) Condenser coil
W) Outside air intake
X) Compressor
A restriction at some point in the liquid line will result in frosting at the point of the restriction. This can be explained best by:
Y) The refrigerant reverses direction.
Z) A pressure drop occurs.
AA) The refrigerant condenses at that point.
The most commonly used method of defrost in a heat pump is:
BB) The bypassing of a portion of hot discharge gas through a loop around the outdoor coil.
CC) The activation of a resistance heater in the outdoor unit.
DD) The reversal of the system refrigerant flow.
EE) The reversal of the out-door fan to blow the ice off the outdoor coil.
When a heat pump goes into the defrost cycle:
FF) The outdoor fan motor continues to operate.
GG) The out-door fan motor stops and the indoor blower circulates air across a resistance heater -element.
HH) Both outdoor and indoor fan motors are de-energized to expedite defrost.
II) The indoor fan stops and supplemental heat is energized.
The main intent of emergency heat is:
JJ) To provide instant warm-up
KK) To provide some tempering heat at defrost.
LL) To provide standby heater operation in compressor failure.
MM) To speed up defrosting of the evaporator coil at sub-zero temperatures.
Refrigerant .22, in the presence of an open flame will:
NN) Put the flame out.
OO) Change to a non-toxic gas.
PP) Change to a toxic gas.
QQ) Explode.
Your checking an oil sample from a hermetic compressor and you determine that you have a sever burnout. You decide to:
RR) Call your boss for help.
SS) Remove and replace the entire condensing unit.
TT) Dump the oil from the compressor and recharge it with fresh oil.
UU) Wear rubber gloves and safety glasses to remove and replace the compressor.
All air conditioning units must be grounded electrically to:
VV) Complete the control circuit.
WW) Prevent electrical shock.
XX) Provide a source of low voltage.
YY) Improve operating efficiency.
You are working on a system with a system with a P.S.C. compressor motor and stop the system to make an adjustment. You throw the switch back on in a few minutes and the compressor refuses to start. It hums and goes out on overload. Your gauges read 187 lb. On the high side and 65 lb. On the low side. Why won’t the compressor start?
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The amount of air delivered through the indoor coil of a heat pump system should be approximately:
ZZ) The same as through the outdoor coil.
AAA) 350 to 450 cfm per ton
BBB) 850 to 950 cfm per ton
CCC) 200 to 300 cfm per ton
DDD) 600 to 700 cfm per ton
A condenser fan motor failure, when the outdoor ambient air temperature is high, will cause:
EEE) The low-pressure safety switch to open.
FFF) High head pressures.
GGG) Seating of liquid line
HHH) The evaporator to frost over.
What is a sling psychrometer?
III) A wall-mounted wall recorder that has a built in sling to catch particles heavier that air (chromets).
JJJ) A humidity-measuring device with wet and dry bulb thermometers which is moved rapidly through the air when measuring humidity.
KKK) A strap-type sling for mounting compressors on the wall.
LLL) None of the above.
What is latent heat?
MMM) The heat required to raise the temperature of a vapor.
NNN) The heat given off in the compressor as heat of compression.
OOO) The heat required to change the state of a substance.
PPP) The heat that you measure with a thermometer.
Water columns are used to measure?
QQQ) Hose pressure.
RRR) Volume.
SSS) Small Pressures, above or below atmospheric.
TTT) Square area.
Gas is superheated as it leaves the?
UUU) Metering device.
VVV) Discharge line.
WWW) Condenser
XXX) Evaporator
In the operation of a thermostatic expansion valve, which is true:
A) The pressure of the bulb fluid acts to open the valve.
B) The pressure of the refrigerant in the evaporator acts to open the valve
C) The spring acts with the evaporator pressure to keep the valve open in relation to the amount of superheat setting.
High suction pressure and low head pressure indicates that the compressor is in deficient in:
D) Refrigeration gas
E) Oil charge
F) Pumping capacity
31) Use the following diagram to label the basic refrigeration cycle, state the connecting lines with proper names of the components and state of the refrigerant in each component and each line:
a)
g)
f) b)
c)
d)
e)
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