問題一覧
1
The amount of latent heat required to change 1 lb of water to 1 lb of steam
970 btu
2
The amount of latent heat required to change one pound of water to 1 lb of ice
144 btu
3
Which method of charging should be used when working on an air conditioning system utilizing a TX valve
Sub cooling method
4
Which method of charging should be used when working on an air conditioning system utilizing a fixed orifice
super heat method
5
A heat pump with a reversing valve that is leaking internally will cause
high suction pressure and low discharge pressure
6
If a new air conditioning system is installed with a 45-ft line set and the unit is pre-charged with a refrigerant for a 15-ft line set in the insulation instructions indicate to add 6 oz for each additional foot of line set to correctly charge the equipment the technician would
at 18 Oz (1 lb 2 oz) of refrigerant
7
The most common type of compressor found in a residential air conditioning is
permanent split capacitor
8
The type of soft copper used in residential air conditioning system is
type L
9
The capacitor on a capacitor start induction run compressor is
in series with the start winding
10
The vacuum pump is used too
remove oxygen and moisture from the air conditioning system
11
A clogged furnace air filter will cause
low suction line pressure
12
Which revision listed below will not deplete the ozone layer
R410A
13
HFC refrigerant do not contain
Chlorine
14
When the line set on an installed air conditioning system is longer than 50 ft and length the technician should
refer to the insulation instructions
15
The term LRA stands for
locked rotor amperage
16
The electrical supply to residential gas furnace is
120v, 1 phase, 60 Hz
17
The contacts on a potential relay are?
normally closed
18
Cooling anticipators are resistors in the thermostat that
provide a false heat load in the off-cycle of the air conditioning system
19
The minimum CFM required across an evaporator in an air conditioning system
350 CFM
20
If an air conditioning system is not functioning in your call to a service equipment the following parameters are found 1. Compressor not operating 2. condenser fan not operating 3. 24 volts found across the contactor coil 4. 240 volts found on the line side of the contactor 5. 120 volts found across contacts 6. 1.2ohms reading across condenser fan motor windings 7. 1.5ohms reading across compressor R & C windings, 3ohms S and R compressor S and C windings and 4.5ohms across S and R windings 8. Compressor capacitor reads 33uf (35 is normal) 9. Condenser fan capacitor reads 4.8uf (5 is normal) What is the problem?
the contactor is defective
21
If an air conditioning system is not functioning in your call to the service the equipment the following parameters are found X. Compressor not operating XI. Condenser fan operating XII. 24 volts found across contactor coil XIII. 240 volts found on the line side of the contactor XIV. 0 volts found across contactors contacts XV. 1.2ohms reading across condenser fan motor windings XVI. Infinity ohms reading a cross compressor RNC windings, Infinity readig across S & C windings, 4.5ohms reading across S&R compressor windings XVII. Compressor capacitor reads 33ohms (35 is normal) XVIII. Condenser fan capacitor reads 4.8 ohms (5 is normal)
the compressor has thermal overload
22
If an air conditioning system is not functioning in your your call to a service equipment the following parameters are found 1. Compressor not operating 2. Condenser fan operating 3. 24 volts found across contact coil 4. 240 volts found on the line side of the contactor 5. 0 volts found a cross contactor contacts 6. 1.2ohms reading across condenser fan motor windings 7. 1.5ohms reading across compressor R & C windings, 3.0ohms reading across compressor S & C windings, 4.5ohms reading across S & R windings 8. Compressor capacitor reads OL (35uF is normal) 9. Condenser fan capacitor reading 4.8uF (5uF is normal)
the compressor capacitor is defective
23
Relays are not available in what?
triple throw models
24
On a combination fan and limit control the three tabs represent looking from left to right on the control
fan off, fan on, high limit
25
The w terminal on the board of a furnace is used to
enable the gas valve
26
Which of the following terms best describes recovery
take refrigerant out of the air conditioning unit and place it in an approved container
27
Which of the following terms best describes recycle
take refrigerant out of the air conditioning unit and place it and approved container put the refrigerant through an on-site oil separation distillation process and return the refrigerant to the system once prepared
28
Hcfc refrigerants will not be available after
in January 1st 2030
29
CFC refrigerants will not be available after
CFC refrigerants are already banned
30
Which of the following terms best describe reclaim
take refrigerant out of the air conditioning unit and place it in approved container send refrigerant off site for oil separation and distillation process in the refrigerant is sold back to the industry as a new refrigerant
31
Which method of charging should be used when working on air conditioning system utilizing a TX valve
subcooling method
32
Which method of charging should be used when working on an air conditioning system utilizing a fixed orifice
superheat method
33
Which of the following terms best to scratch reuse
take refrigerant out of the air conditioning unit and place it in an approved container and return the refrigerant to the system once repaired
34
Heating and cooling thermostats react to
sensible heat only
35
The closing force of the TX valve is provided by
evaporator pressure
36
The opening force of a TX valve is provided by
the sensing ball pressure
37
What condition could cause liquid refrigerant to load backup to the condenser
metering device offices to restrictive
38
If an a evaporator coil is found with one half frosting and the other half condensating what is the problem
one of the capillary tubes is plugged
39
If the water regulating valve on a water cool condensers restricted the head pressure will
increase
40
If a 5uf capacitor and 15uf capacitors are placed in series with each other the resulting capacitance will be
3.75uf
41
If a 5uf capacitor in a 15uf good pastor our place in parallel with each other the resulting capacitor will be
20uf
42
Condensing refrigerant
change of States not temperature
43
The amount of latent heat required to change 1 lb of water to 1 lb of steam is
970 BTU
44
The amount of latent heat required to change 1 lb of water to 1 lb of ice is
144 BTU
45
Sensible heat is defined as
a change of temperature of a substance without change of state
46
Latent heat is defined as
a change of state of a substance without a change of temperature
47
Enthalpy is defined as
the total amount of heat removed to change the substance
48
A 35uf, 440v capacitor is faulty in a residential air conditioning unit the technician could replace a capacitor with which of the following choices placed in parallel with each other
20uf, 440v capacitor, 12.5uf 570v capacitor
49
The technician must replace a 40uf, 440v capacitor,
38uf, 440v capacitor
50
Heat anticipators are
installed in series with the gas valve
51
No suction pressure in the air conditioning system could be caused by
all the above
52
Evaporating substance
will absorb heat
53
Superheat is found
in the suction line
54
Proper amount of subcooling indicates
proper refrigerant charge, condenser functioning properly
55
Proper amount of superheat indicates
proper refrigerant charge, evaporator functioning properly
56
Which of the following refrigerants is a blend of different refrigerants
R 410A
57
Crankcase heater is used for
prevents liquid from migrating in the compressor
58
Electricity is the flow of
Valencia electrons
59
The motor and compressor loads require which types of fuses
Type D fuse
60
Fuse are connected
in series with the load being protected
61
A reading of 0 volts is obtained across an energized fuse which means
fuse is good
62
Fuse will blow if excessive................. is present?
amperage
63
Electromotive force is measured using
voltmeter
64
The wiring found in a residential breaker panel is
240/120 volt, 1 phase, 60 Hz
65
As a humidity and a condition space rises, the temperature difference across evaporator will?
decrease
66
When fresh air is introduced to a home for ventilation purposes
all of the above
67
Which of the following gases is the most dangerous to pressure test and air conditioning system wet
oxygen
68
fractionation is a concern when using?
R410A
69
Which of the following instruments is used to measure inches of water column?
manometer
70
Which of the following instrument utilizes a hot wire?
Anemomter
71
Which of the following instruments is used to measure wet bulb temperature?
psychrometer
72
On the diagram on the previous page the refrigerant should be in what state at point a
low pressure, medium temperature, vapor
73
On the diagram on the previous page the refrigerant should be in what state at point b
high pressure, high temperature, vapor
74
On the diagram on the previous page the refrigerant should be in what state at point C
high pressure, medium temperature, liquid
75
In the diagram the refrigerant should be at what state at point D
low pressure, low temperature, liquid
76
Which of the following devices would help solve low suction pressure conditions
low ambient control
77
A magnahelic gauge can be used to determine
duck static pressure CFM
78
If an air conditioning system has a non-bleed t type TXV valve installed, what component should also be installed on the compressor
hard start kit
79
Which of the following conditions will cause the head pressure to rise
low condenser air flow
80
Which of the following conditions can cause evaporator to freeze up
Open bypass humidifier damper
81
If a technician finds a zone damper motor that is seized what should be done?
replace the damper motor, reactivate, and test the damper motor
82
A zone damper that fails to open could cause
can cause low suction pressure for a heat pump in cooling mode
83
A reversing valve on a heat pump has
2 inlets and 2 outlets
84
The main reason for nitrogen spewing during grazing is
to remove oxygen from inside at the tubing
85
A reversing valve that has an internal leak will cause
decrease in the liquid temperature in the condenser
86
The first law of thermodynamics states
heat cannot be created or destroyed
87
Which of the following is a concern with r410a
operating pressures are much higher than r22
88
How much refrigerant pressure is required to change the position of the reversing valve on a heat pump
75 PSI
89
The definition of BTU is?
the amount of heat required to raise 1 lb of water 1° f
90
If the suction pressure is 72 PSIG in the suction temperature line is 42° f in a r22 system the compressor is safe?
no, because liquid vision could enter the compressor
91
An equalizing line on an external equalizing TX valve will connect the valve body to
evaporate outlet downstream of the sensing bulb
92
The reversing valve is found?
on a heat pump system
93
He probably operating reversing valve well
only change positions on a call for a cooling
94
Charging system with r410a
both A and C
95
Is it ever acceptable to install an evaporator in the return air duct of a furnace
yes
96
When implying heat to a joint being a braised what vision will indicate that joint is hot enough to add filler alloy
the flux will turn to a clear liquid
97
Copper tubing glows red in color at what temperature
1800 degrees Fahrenheit
98
When checking for continuity the meter use would be
ohmmeter
99
When checking for current the meter use would be
ammeter
100
When checking for resistance the meter use would be
ohm meter