Review Questions for Grade 4 Refrigeration

How do you test the high limit in a furnace during a maintenance?

• Make a call for heat and stop the airflow.

• Increase the airflow to maximum.

• Check the thermostat settings.

• Inspect the furnace for physical damage.

What is the best method to determine if a drain line heater for a freezer is operating properly?

• Use an ammeter

• Check the temperature of the freezer

• Inspect the drain line visually

• Listen for unusual noises from the heater

Where is a Snap Acting Device used?

• It could be a two position or any on off switch

• In complex multi-position control systems

• For continuous variable control applications

• As a safety interlock mechanism

How could you repair a leak at the stem of a suction service valve on a refrigeration system?

• Replace the entire valve assembly.

• Tighten the packing gland and recheck for leaks.

• Apply sealant around the valve stem.

• Increase the pressure in the system.

Where to install a vibration isolator in a refrigeration system?

• Parallel to the crankshaft

• At the compressor outlet

• Near the evaporator

• Before the condenser

What is a Primary consideration when installing a roof top unit

• Roof Pitch

• Temperature Control

• Aesthetic Design

• Cost of Installation

How to test an OFC?

• Use jumper 1 & 2 to keep the heater on.

• Perform a visual inspection of the OFC.

• Check the voltage levels with a multimeter.

• Run a software diagnostic test.

When selecting and installing power supply wiring to a refrigeration fixture what must be done if the length of the wire between the fixture and the wiring panel exceed 100 feet?

• Increase the wire size by one size.

• Decrease the wire size by one size.

• Use the same wire size regardless of length.

• Install a second wire in parallel.

How do you adjust a CPR?

• Do it under heavy load.

• Increase the compressor speed.

• Lower the ambient temperature.

• Set the valve to maximum pressure.

How to calculate the percentage of outside air using 3 temperature sensors?

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