60-4

A(n) __________ refrigerant pressure differential indicates that frost or ice has formed on the evaporator and initiates a defrost cycle.

Select one:

• a.Increasing

• b.Reciprocating

• c.Decreasing

• d.Changing

Technician A says that when the three-way valve is de-energized, spring pressure moves the valve to a heating position. Technician B says that when the three-way valve is energized, gas pressure forces the valve into the cooling mode. Who is correct?

Select one:

• Tech A

• Tech B

• Both Techs

• Neither

Most units will not enter the defrost mode unless the evaporator coil temperature is below approximately ____________.

Select one:

• a.45°F (7.2°C)

• b.65°F (18°C)

• c.60°F (16°C)

• d.55°F (12.8°C)

The defrost mode in  truck-transport temperature control systems is terminated when coil temperature rises to __________.

Select one:

• a.0°F (–18°C)

• b.45°F (7.2°C)

• c.–20°F (–29°C)

• d.55°F (12.8°C)

Which of the following can supplement heating capacity of the refrigeration system in heat mode?

Select one:

• a.Electrically operated solenoids

• b.Electric heaters

• c.Operational electric stand-by systems

• d.Electric motors