What tool should be used to shorten a capillary tube? - ANSWERS-A triangular or
knife-edge file
Which pressure in a TXV is the opening pressure? - ANSWERS-Bulb Pressure
What effect does a low refrigerant charge have on reversing valve operation? -
ANSWERS-It increases the chance that the reversing valve will not be able to
transfer properly
Which of the following should be used to leak-test refrigerant tubing? -
ANSWERS-Dry nitrogen
Of the motors commonly used in HVACR systems, which type has the lowest
starting torque? - ANSWERS-Shaded-Pole Motor
Voltage supplied to a motor may vary from the rated voltage by _____% -
ANSWERS-d (+10%, -10%)
What is one of the most important reasons for using electronic controls in HVACR
systems? - ANSWERS-They make decisions based on many inputs
,Hard-start kits are often needed on _______. - ANSWERS-Reciprocating
compressors used with TEVs
A 24v transformer with a 40 VA rating can safely operate with a current of
________. - ANSWERS-1.67 Amps
According to Ohm's Law, what will happen if voltage to a heater element is
increased 10%? - ANSWERS-The current draw will increase by 10%
When the airflow through an electric heater is insufficient, the technician will
observe_______. - ANSWERS-Heater elements glowing red or orange
Which combination of measurements indicates an open heater element? -
ANSWERS-Voltage to the heater with no current draw through the heater
elements
What internal voltage is likely to be measured in an electronic air cleaner? -
ANSWERS-5000V
What problem is likely to occur if a proper trap is not used on the condensate
drain for a pull-through unit? - ANSWERS-Condensate water will not drain
properly and will back up above the primary drain
What issues affect the decision to use a running trap on a
, condensate line at the evaporator coil? - ANSWERS-Running traps do not allow for
the proper drainage of condensate water
The auxiliary drain line from an overflow pan must _________. - ANSWERS-be
terminated at some conspicuous location so that an overflow is readily noticed
Which of the following brazing materials is acceptable for use on a
refrigerant piping? - ANSWERS-Brazing allow with an approved flux
Why must you exercise caution when bending soft-drawn refrigerant tubing? -
ANSWERS-Any distortion of the tubing diameter creates a restriction to
refrigerant flow that reduces system capacity
What voltage is measured between any two hot legs on a 3-phase 240V
distribution panel? - ANSWERS-240V
What is the indoor air flow for an electric furnace when the supply air
temperature is 98 F, the return air temperature is 70 F, the voltage supplied to
the furnace is 220V, and the current draw of the furnace is 47 A? - ANSWERS-
1,170 CFM
Note:
CFM = Btuh / (1.08 x TD)
Btuh = W x 3.413
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