HVAC Air Handler Units and Coils 2

Question 1

What is the primary purpose of a drain pan in an air handler unit?

Accepted Answer

To collect condensate from the evaporator coil

Answer

The drain pan collects condensate water that forms on the evaporator coil during the cooling process and channels it to the drain line.

Question 2

Which type of air handler configuration has the blower located downstream of the coil?

Accepted Answer

Draw-through

Answer

In a draw-through configuration, the blower pulls air through the coil rather than pushing it, which is the most common arrangement.

Question 3

What causes a evaporator coil to freeze up during operation?

Accepted Answer

Restricted airflow or low refrigerant charge

Answer

Restricted airflow (dirty filter, closed registers) or low refrigerant charge causes suction pressure to drop below freezing, causing the coil to ice over.

Question 4

What is the function of a TXV (thermostatic expansion valve) in relation to the evaporator coil?

Accepted Answer

It meters refrigerant flow into the coil based on superheat

Answer

The TXV meters refrigerant flow into the evaporator coil by sensing superheat, ensuring the coil operates efficiently without liquid refrigerant returning to the compressor.

Question 5

When installing an air handler in a vertical upflow position, where should the evaporator coil be located?

Accepted Answer

At the top of the unit above the blower

Answer

In a vertical upflow air handler, the blower is at the bottom and the evaporator coil is at the top so air flows upward through the coil.

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC Air Handler Units and Coils 2