CDC 3E151 HVAC/R JOURNEYMAN VOLUME 1-5
|ACTUAL QUESTIONS AND VERIFIED
ANSWERS|BRAND NEW 2026-2027
UPDATE|GRADED A+
Question 1
(001) When using a halide leak detector, the bluish flame turning green indicates
CORRECT ANSWER
a refrigerant leak
Question 2
(001) On a manifold gauge assembly, the vacuum hose is 3/8 inch and the other hoses are
1/4 inch because larger sizes allow for
CORRECT ANSWER
fewer restrictions which makes it easier and quicker to pull a vacuum
Question 3
(001) Why should the manifold gauge assembly not be used when measuring a vacuum?
CORRECT ANSWER
The gauge assembly reads inches of mercury and is not accurate when pulling deep vacuums
Question 4
(002) While taking a reading with an infrared thermometer, what happens as you get
further from the object being measured?
1
,CORRECT ANSWER
The reading becomes more inaccurate
Question 5
(003) What part of the combustion analyzer gets placed into the stack?
CORRECT ANSWER
The probe
Question 6
(003) What transfers flue gases from the boiler stack to the indicator unit?
CORRECT ANSWER
A tube and hand bulb
Question 7
(003) The special slide-rule calculator and CO2 indicator are used to determine
CORRECT ANSWER
combustion efficiency and stack loss
Question 8
(004) What will occur if you choose more than one conductor to measure when using a
clamp on meter?
CORRECT ANSWER
Incorrect readings
2
,Question 9
(004) A megohmmeter should never be used on a live circuit because
CORRECT ANSWER
it has its own power source and it will ruin the meter
Question 10
(004) A capacitance checker is used to test
CORRECT ANSWER
a capacitor
Question 11
(005) A photo tachometer is used to read the
CORRECT ANSWER
revolutions per minute (RPM) of a spinning motor shaft
Question 12
(005) When using a stroboscope, the frequency and reading is displayed for the technician
when the object appears to be
CORRECT ANSWER
standing still and the rpm of the equipment matches
3
, Question 13
(005) What pressure will be given if both tubes are connected to the inclined manometer?
CORRECT ANSWER
Velocity pressure
Question 14
(005) Magnehelic pressure gauges were developed to
CORRECT ANSWER
overcome the disadvantages of the inclined and the inclined vertical manometers
Question 15
Why does the magnehelic gauge need more frequent calibration?
CORRECT ANSWER
Because it is a mechanical instrument and is sensitive to physical abuse, dirt, dust, corrosive
gases, and fluids
Question 16
(005) Why is the accuracy at filters, louvers, and coils very rough?
CORRECT ANSWER
Due to the uncertainty of the Ak ( correction factor) area
Question 17
(005) In order to be measured by the flow hood, how is all of the air forced to flow
through the diffuser or grille?
4
|ACTUAL QUESTIONS AND VERIFIED
ANSWERS|BRAND NEW 2026-2027
UPDATE|GRADED A+
Question 1
(001) When using a halide leak detector, the bluish flame turning green indicates
CORRECT ANSWER
a refrigerant leak
Question 2
(001) On a manifold gauge assembly, the vacuum hose is 3/8 inch and the other hoses are
1/4 inch because larger sizes allow for
CORRECT ANSWER
fewer restrictions which makes it easier and quicker to pull a vacuum
Question 3
(001) Why should the manifold gauge assembly not be used when measuring a vacuum?
CORRECT ANSWER
The gauge assembly reads inches of mercury and is not accurate when pulling deep vacuums
Question 4
(002) While taking a reading with an infrared thermometer, what happens as you get
further from the object being measured?
1
,CORRECT ANSWER
The reading becomes more inaccurate
Question 5
(003) What part of the combustion analyzer gets placed into the stack?
CORRECT ANSWER
The probe
Question 6
(003) What transfers flue gases from the boiler stack to the indicator unit?
CORRECT ANSWER
A tube and hand bulb
Question 7
(003) The special slide-rule calculator and CO2 indicator are used to determine
CORRECT ANSWER
combustion efficiency and stack loss
Question 8
(004) What will occur if you choose more than one conductor to measure when using a
clamp on meter?
CORRECT ANSWER
Incorrect readings
2
,Question 9
(004) A megohmmeter should never be used on a live circuit because
CORRECT ANSWER
it has its own power source and it will ruin the meter
Question 10
(004) A capacitance checker is used to test
CORRECT ANSWER
a capacitor
Question 11
(005) A photo tachometer is used to read the
CORRECT ANSWER
revolutions per minute (RPM) of a spinning motor shaft
Question 12
(005) When using a stroboscope, the frequency and reading is displayed for the technician
when the object appears to be
CORRECT ANSWER
standing still and the rpm of the equipment matches
3
, Question 13
(005) What pressure will be given if both tubes are connected to the inclined manometer?
CORRECT ANSWER
Velocity pressure
Question 14
(005) Magnehelic pressure gauges were developed to
CORRECT ANSWER
overcome the disadvantages of the inclined and the inclined vertical manometers
Question 15
Why does the magnehelic gauge need more frequent calibration?
CORRECT ANSWER
Because it is a mechanical instrument and is sensitive to physical abuse, dirt, dust, corrosive
gases, and fluids
Question 16
(005) Why is the accuracy at filters, louvers, and coils very rough?
CORRECT ANSWER
Due to the uncertainty of the Ak ( correction factor) area
Question 17
(005) In order to be measured by the flow hood, how is all of the air forced to flow
through the diffuser or grille?
4
