UA HVAC Star Exam Questions And
Correct Answers (Verified Answers) Plus
Q&A | Instant Download Pdf
Doesn't evaporator reject heat from the condition space? - ANSWER -No, the
evaporator absorbs heat from the conditioned Space.
Heat that is added to the refrigerant stream after the 100% saturated vapor point is
called - ANSWER -Super heat
Multiple refrigerant circuits are preferred on evaporators that are - ANSWER -
Large and long
In a system where the evaporator temperature operates above 32° the technician
does not need to be concerned with - ANSWER -Defrost
The fin spacing per inch on a medium temperature evaporator is - ANSWER -
Closer together than on low temperature evaporators because there's less potential
for Frost build up
A refrigeration system that utilizes two or three stages of low temperature
refrigeration is called - ANSWER -Cascade system
When leak testing a refrigeration system using a high-pressure nitrogen tank
technician should always use - ANSWER -A pressure regulator and safety relief
valve at the nitrogen tank
The maximum pressure that can be applied to a refrigeration system when
pressure testing is determined by - ANSWER -The system is rated nameplate test
pressures
The safest way to charge refrigerant into a system that is running is with -
ANSWER -Vapor into the low side
,When heating a refrigerant cylinder, the technician should never use - ANSWER -
Any type of open flame
Refrigeration systems must be fully evacuated before charging with refrigerant
because - ANSWER -Need to remove air and moisture from the system. All
noncondensibles.
A vacuum pump will lose its ability to draw a deep vacuum overtime because -
ANSWER -The oil becomes full of moisture and acids which decrease the
capability of the vacuum pump
A refrigerant service valve must be placed in what position do access the system -
ANSWER -Mid position
What level should a system be evacuated to to ensure that noncondensibles and
moisture have been removed? - ANSWER -500 microns
Amperage is a measure of - ANSWER -Electron flow
Voltage is the measure of - ANSWER -Electrical pressure
Wattage is a measure of - ANSWER -Electrical power. One watt equals 3.41
BTUs.
746 W equals - ANSWER -One horsepower
1 kW is equal to how many BTUs - ANSWER -3412
The unit of measurement for magnetic flux is - ANSWER -Maxwell
On a resistive electrical circuit which law would be used to calculate I E or R -
ANSWER -Ohms law
Which of the following formula would be used to calculate amperage in a
resistance circuit? - ANSWER -I=RE
Capacitance represents a component ability to - ANSWER -Store electrons
A meter with a capacity to measure very high resistance is called a - ANSWER -
Megger
,A technician would use a micron gauge to measure - ANSWER -A deep vacuum
If a technician has set his VOM to read Rx100 he would be measuring -
ANSWER -Resistance
When checking resistance through a motor winding the proper instrument to use
would be a - ANSWER -Ohmmeter
An ohmmeter will measure infinite resistance when testing - ANSWER -Open
fuses and open Contacts
If the technician has placed his VOM and parallel with an energize load, he is
probably checking - ANSWER -Voltage
If a technician has placed his VOMN series with the load, he is probably checking
- ANSWER -Amperage
Which of the following instruments will be used to check the condition of
insulation on a Motors windings - ANSWER -Megohmmeter
A ladder diagram can also be called - ANSWER -Electrical line wiring diagram
A pictorial diagram will show - ANSWER -Approximate locations of the
electrical system components
The primary and secondary windings in a transformer are wired in series, parallel,
or not connected? - ANSWER -Not connected electrically
What happens when the length of the path of an electrical circuit is decreased? -
ANSWER -There will be a decrease in total circuit resistance
What is the total amperage of a circuit when two 25 ohm resistors are connected in
series using a 120 v power source - ANSWER -2.4 amps. Total resistance is added
then divided into voltage. 120/50
If the voltage is the same across each load in a serpent, it would be considered
what type of circuit? - ANSWER -Parallel
, If a circuit is designed to allow the flow of electrons to follow only one path it
would be called. What type of circuit - ANSWER -Rectifier circuit. He rectifier
allows current to flow in One Direction because of this the output of a rectifier
circuit is in one direction, thereby converting AC current to DC.
A line or ladder type diagram is most useful for understanding what? - ANSWER
-Circuit operation
If the technician looks at a reading across a normally close set of contacts when a
relay or contactor cord was deenergized, the reading would be? - ANSWER -0 V
An ohmmeter must never be connected to what? - ANSWER -An energize circuit
If a 24 V control transformer has a VA rating of 60 what is the maximum
amperage rating? - ANSWER -2.5 A. VA stands for volt amps if you divide the
rated voltage of the transformer into VA you will get the amount of amps that the
transformer can handle.
A current relay as what type of contacts - ANSWER -Normally open
Another term for a motor starter is - ANSWER -Motor controller
If a relay coil is open, the technician would read what on his ohmmeter? -
ANSWER -Infinite or zero resistance
A sensor that uses positive temperature coefficient thermistor does what to
resistance as temp increases? - ANSWER -Increases resistance as temperature
increases
These devices are used to protect electrical circuits from overcurrent - ANSWER
-Fuses and breakers
If two 30 microfarad run capacitor are wired in parallel. What is the new
microfarad rating? - ANSWER -60
On a hermetic compressor what component is designed into
The compressor to protect against excessive temperatures and overtime -
ANSWER -An overload protector
The Contacts of a potential relay are - ANSWER -Normally closed
Correct Answers (Verified Answers) Plus
Q&A | Instant Download Pdf
Doesn't evaporator reject heat from the condition space? - ANSWER -No, the
evaporator absorbs heat from the conditioned Space.
Heat that is added to the refrigerant stream after the 100% saturated vapor point is
called - ANSWER -Super heat
Multiple refrigerant circuits are preferred on evaporators that are - ANSWER -
Large and long
In a system where the evaporator temperature operates above 32° the technician
does not need to be concerned with - ANSWER -Defrost
The fin spacing per inch on a medium temperature evaporator is - ANSWER -
Closer together than on low temperature evaporators because there's less potential
for Frost build up
A refrigeration system that utilizes two or three stages of low temperature
refrigeration is called - ANSWER -Cascade system
When leak testing a refrigeration system using a high-pressure nitrogen tank
technician should always use - ANSWER -A pressure regulator and safety relief
valve at the nitrogen tank
The maximum pressure that can be applied to a refrigeration system when
pressure testing is determined by - ANSWER -The system is rated nameplate test
pressures
The safest way to charge refrigerant into a system that is running is with -
ANSWER -Vapor into the low side
,When heating a refrigerant cylinder, the technician should never use - ANSWER -
Any type of open flame
Refrigeration systems must be fully evacuated before charging with refrigerant
because - ANSWER -Need to remove air and moisture from the system. All
noncondensibles.
A vacuum pump will lose its ability to draw a deep vacuum overtime because -
ANSWER -The oil becomes full of moisture and acids which decrease the
capability of the vacuum pump
A refrigerant service valve must be placed in what position do access the system -
ANSWER -Mid position
What level should a system be evacuated to to ensure that noncondensibles and
moisture have been removed? - ANSWER -500 microns
Amperage is a measure of - ANSWER -Electron flow
Voltage is the measure of - ANSWER -Electrical pressure
Wattage is a measure of - ANSWER -Electrical power. One watt equals 3.41
BTUs.
746 W equals - ANSWER -One horsepower
1 kW is equal to how many BTUs - ANSWER -3412
The unit of measurement for magnetic flux is - ANSWER -Maxwell
On a resistive electrical circuit which law would be used to calculate I E or R -
ANSWER -Ohms law
Which of the following formula would be used to calculate amperage in a
resistance circuit? - ANSWER -I=RE
Capacitance represents a component ability to - ANSWER -Store electrons
A meter with a capacity to measure very high resistance is called a - ANSWER -
Megger
,A technician would use a micron gauge to measure - ANSWER -A deep vacuum
If a technician has set his VOM to read Rx100 he would be measuring -
ANSWER -Resistance
When checking resistance through a motor winding the proper instrument to use
would be a - ANSWER -Ohmmeter
An ohmmeter will measure infinite resistance when testing - ANSWER -Open
fuses and open Contacts
If the technician has placed his VOM and parallel with an energize load, he is
probably checking - ANSWER -Voltage
If a technician has placed his VOMN series with the load, he is probably checking
- ANSWER -Amperage
Which of the following instruments will be used to check the condition of
insulation on a Motors windings - ANSWER -Megohmmeter
A ladder diagram can also be called - ANSWER -Electrical line wiring diagram
A pictorial diagram will show - ANSWER -Approximate locations of the
electrical system components
The primary and secondary windings in a transformer are wired in series, parallel,
or not connected? - ANSWER -Not connected electrically
What happens when the length of the path of an electrical circuit is decreased? -
ANSWER -There will be a decrease in total circuit resistance
What is the total amperage of a circuit when two 25 ohm resistors are connected in
series using a 120 v power source - ANSWER -2.4 amps. Total resistance is added
then divided into voltage. 120/50
If the voltage is the same across each load in a serpent, it would be considered
what type of circuit? - ANSWER -Parallel
, If a circuit is designed to allow the flow of electrons to follow only one path it
would be called. What type of circuit - ANSWER -Rectifier circuit. He rectifier
allows current to flow in One Direction because of this the output of a rectifier
circuit is in one direction, thereby converting AC current to DC.
A line or ladder type diagram is most useful for understanding what? - ANSWER
-Circuit operation
If the technician looks at a reading across a normally close set of contacts when a
relay or contactor cord was deenergized, the reading would be? - ANSWER -0 V
An ohmmeter must never be connected to what? - ANSWER -An energize circuit
If a 24 V control transformer has a VA rating of 60 what is the maximum
amperage rating? - ANSWER -2.5 A. VA stands for volt amps if you divide the
rated voltage of the transformer into VA you will get the amount of amps that the
transformer can handle.
A current relay as what type of contacts - ANSWER -Normally open
Another term for a motor starter is - ANSWER -Motor controller
If a relay coil is open, the technician would read what on his ohmmeter? -
ANSWER -Infinite or zero resistance
A sensor that uses positive temperature coefficient thermistor does what to
resistance as temp increases? - ANSWER -Increases resistance as temperature
increases
These devices are used to protect electrical circuits from overcurrent - ANSWER
-Fuses and breakers
If two 30 microfarad run capacitor are wired in parallel. What is the new
microfarad rating? - ANSWER -60
On a hermetic compressor what component is designed into
The compressor to protect against excessive temperatures and overtime -
ANSWER -An overload protector
The Contacts of a potential relay are - ANSWER -Normally closed
