Question 1

The brain of the frost-free appliance is the defrost relay.

Accepted Answer

The defrost timer or control board is typically considered the brain of a frost-free appliance, not the defrost relay. The defrost relay is a component within the defrost system that controls the operation of the defrost heater.

Question 2

Many large commercial refrigeration units often use a separate timer clock to control the defrost cycle.

Accepted Answer

This is true as many commercial refrigeration units are equipped with a separate timer clock to control the defrost cycle, which helps prevent the build-up of ice on the evaporators and ensures the unit operates efficiently.

Question 3

Two basic connections for a defrost timer are: the ____ and the cumulative compressor run timer.&#10;A) electromechanical timer&#10;B) thermal timer&#10;C) continuous run timer&#10;D) countdown timer

Accepted Answer

continuous run timer

Question 4

The motor of the ____ is connected directly to the power line and runs at all times.&#10;A) electromechanical timer&#10;B) continuous run timer&#10;C) thermal timer&#10;D) cumulative compressor run timer

Accepted Answer

The description of the motor being connected directly to the power line and running at all times fits the definition of a continuous run timer. The other choices refer to different types of timers that have different functions.

Question 5

The motor of the cumulative compressor run timer is permitted to operate only when the compressor is in operation and the ____.&#10;A) thermostat is closed&#10;B) fan is in low speed&#10;C) expansion valve is closed&#10;D) dryer is saturated

Accepted Answer

The thermostat being closed indicates that the desired temperature has not been reached yet, which means the compressor needs to continue running. Therefore, the timer motor should be permitted to operate only when the compressor is in operation and the thermostat is closed. The other choices are unrelated to the operation of the compressor run timer.

Question 6

Defrost timers generally have several timed settings.

Accepted Answer

Defrost timers typically have a single fixed cycle that controls the defrosting schedule, not multiple timed settings.

Question 7

The defrost timer is operated by a single-phase synchronous motor.

Accepted Answer

The defrost timer is typically operated by a single-phase synchronous motor, which allows it to keep accurate time and cycle the defrost operation on and off as needed.

Question 8

The cam can be manually turned to the position so that the defrost cycle is turned on.

Accepted Answer

The cam can be manually turned to initiate the defrost cycle.

Question 9

The defrost timer contacts are operated by a(n) ____ that is gear-driven by an electric wall clock motor.&#10;A) lever&#10;B) shaft&#10;C) eccentric disc&#10;D) cam

Accepted Answer

The defrost timer contacts are operated by a cam that is gear-driven by an electric wall clock motor. The cam is designed to turn the contacts on and off at appropriate intervals to ensure that the defrost cycle is performed correctly.

Question 10

The function of the defrost timer is to disconnect the compressor from the circuit and connect a resistive heater located near the ____ at regular intervals.&#10;A) evaporator&#10;B) condenser&#10;C) dryer&#10;D) compressor

Accepted Answer

The defrost timer is responsible for initiating the defrost cycle, during which the compressor is disconnected and a resistive heater located near the evaporator is turned on. This allows the accumulated ice on the evaporator to melt and drain away.

Deck 28: The Defrost Timer