HVAC Air Conditioning 5

Question 1

Which type of air distribution system delivers conditioned air through a single large duct and uses a mixing box at each zone to control temperature?

Accepted Answer

Dual-duct system

Answer

A dual-duct system supplies both cold and hot air through separate ducts to mixing boxes at each zone, where they blend to achieve the desired temperature.

Question 2

A compressor that is 'pumping down' correctly should result in what suction pressure reading?

Accepted Answer

Near 0 psig or slightly into a vacuum

Answer

When pumping down, the compressor evacuates refrigerant from the low side until the suction pressure reaches approximately 0 psig or a slight vacuum, then the low-pressure control shuts it off.

Question 3

What is the primary cause of 'liquid slugging' in an air conditioning compressor?

Accepted Answer

Liquid refrigerant or oil entering the compressor suction

Answer

Liquid slugging occurs when liquid refrigerant or oil enters the compressor suction, and since liquids are incompressible, this can bend connecting rods or break valve reeds.

Question 4

What does a high superheat reading at the evaporator outlet combined with low suction pressure most likely indicate?

Accepted Answer

Restricted metering device or low refrigerant charge

Answer

High superheat with low suction pressure indicates the evaporator is starved of refrigerant, which is caused by a restricted metering device or insufficient refrigerant charge.

Question 5

Which component in a residential split-system air conditioner is responsible for moving air across the indoor coil?

Accepted Answer

Air handler blower motor

Answer

The air handler blower motor (typically a multi-speed or ECM motor) circulates indoor air across the evaporator coil for heat exchange.

HVAC Practice Test

HVAC Practice Test

HVAC Air Conditioning 5