Red Seal Practice Exam Flashcards
When testing a compressor motor winding, what mega-ohm reading indicates the cleanest system?
a) 0
b) 0.2
c) 200
d) 2000
d)
Heat pump has high suction pressure
a) low charge
b) leaking rev valve
c) leaking LLS
d) restricted drier
b)
The enthalpy control on a rooftop air conditioning unit’s economizer is being calibrated. Which instruments are selected?
A. Manometer, ammeter and psychrometer.
B. Manometer, Pitot tube and thermometer.
C. Multimeter, Pitot tube and thermometer.
D. Thermometer, psychrometer and multimeter.
d)
Which cooling coil is selected for maximum dehumidification?
A. 4 row high velocity.
B. 4 row low velocity.
C. 8 row low velocity.
D. 8 row high velocity.
c)
Which type of oil is the most hygroscopic?
A. Naphtha.
B. Mineral oil (MO).
C. Alkylbenzene (AB).
D. Polyolester oil (POE).
d)
Which terminal controls the reversing valve on a heat pump?
A. L/A.
B. O/B.
C. W.
D. Y.
b)
A manual pump down is required. How is the king valve adjusted?
A. Turn the stem clockwise to front seat.
B. Turn the stem clockwise to back seat.
C. Turn the stem counter-clockwise to front seat.
D. Turn the stem counter-clockwise to back seat.
a)
Given the following information:
Parallel compressor system
Compressors are cycling on low pressure controls
Receiver liquid gauge is showing empty
Sight glass is flashing
Head pressure is low
What is the cause?
A. Reed valves are faulty.
B. Split condenser valve is leaking by.
C. Discharge differential valve is leaking by.
D. Oil pressure differential valve is stuck open.
b)
Why is glycol inhibitors added to chilled water loops?
A. To prevent corrosion.
B. To prevent ruptured piping.
C. To increase heat exchange.
D. To decrease bacterial growth.
a)
The crankcase on a semi-hermetic compressor is very hot. What is the cause?
A. TXV (TEV) spring is broken.
B. Piston rings are defective.
C. Oil separator float is seized closed.
D. Liquid line solenoid valve coil is inoperative.
b)
A TXV (TEV) power element capillary tube is cracked. What is the result?
A. High suction pressure.
B. Low evaporator superheat.
C. High compressor superheat.
D. Low compressor discharge temperature.
C)
The rpm of a ducted fan moving 1 200 CFM is increased. What is the result?
A. Fan motor amperage increases and total external static pressure increases.
B. Fan motor amperage increases and total external static pressure decreases.
C. Fan motor amperage decreases and total external static pressure increases.
D. Fan motor amperage decreases and total external static pressure decreases.
A)
The valves have failed on a compressor. What is done?
A. Replace head gasket and valve plate.
B. Replace valve plate gasket and head plate.
C. Replace valve plate gasket, head gasket and head plate.
D. Replace valve plate gasket, head gasket and valve plate.
D)
Which type of refrigerant requires the allowance of glide when calculating superheat?
A. Zeotrope.
B. Azeotrope.
C. Near-zeotrope.
D. Near-azeotrope.
A)
