Ontario Red Seal 313D Exam Preparation Quiz

Which of the following conditions would most likely cause an evaporator coil to freeze?

• Oversized condenser unit

• High refrigerant charge

• Low airflow across the evaporator

• Faulty compressor

When performing a manual pump-down procedure, how should the king valve be positioned?

• Back-seated

• Mid-position

• Front-seated

• Fully closed

A refrigeration system exhibits high suction pressure and low discharge pressure. What is the most probable cause?

• Refrigerant overcharge

• Restricted metering device

• Compressor valve failure

• Air in the system

In a thermostatic expansion valve (TXV), which force primarily controls the opening of the valve?

• Evaporator pressure

• Spring pressure

• Ambient temperature

• Sensing bulb pressure

What is the primary function of a crankcase heater in a compressor?

• Enhance lubrication efficiency

• Increase refrigerant pressure

• Prevent refrigerant migration and mixing with oil

• Reduce compressor noise

During the evacuation of a refrigeration system, which micron level indicates that the system is adequately dehydrated?

• 2,000 microns

• 500 microns

• 1,000 microns

• 1,500 microns

A technician measures a superheat of 5°F at the evaporator outlet. What does this indicate about the system's refrigerant charge?

• Non-condensable gases present

• Properly charged

• Undercharged

• Overcharged

Which type of metering device automatically adjusts to varying load conditions?

• Capillary tube

• Thermostatic expansion valve (TXV)

• Automatic expansion valve (AXV)

• Fixed orifice

What is the effect of non-condensable gases in a refrigeration system?

• Reduced compressor workload

• Elevated discharge pressure

• Increased system efficiency

• Lower suction pressure

When brazing refrigerant lines, which safety precaution is essential to prevent oxidation inside the tubing?

• Applying flux to the joints

• Wearing protective eyewear

• Utilizing a high-temperature torch

• Using a nitrogen purge