310S Heating, Ventilation and Air Conditioning (HVAC) 3

Question 1

The blend door (air mix door) in an HVAC system is primarily responsible for:

Accepted Answer

Controlling the ratio of heated and cooled air to regulate cabin temperature

Answer

The blend door mixes air flowing over the heater core with air bypassing it to achieve the precise cabin temperature set by the driver.

Question 2

What is the recommended service interval for replacing the cabin air filter on most vehicles?

Accepted Answer

Every 15,000–25,000 km or annually

Answer

Most manufacturers recommend replacing the cabin air filter every 15,000–25,000 km or annually to maintain proper HVAC airflow and filter effectiveness.

Question 3

Which vehicle system does the heater core draw its heat energy from?

Accepted Answer

The engine cooling system

Answer

The heater core is plumbed into the engine cooling system; hot coolant flows through it and cabin air passes over its fins to provide passenger compartment heat.

Question 4

A customer reports no heat despite the engine reaching normal operating temperature. Coolant level is correct. What should the technician check NEXT?

Accepted Answer

Heater core coolant flow and blend door actuator function

Answer

If the engine is at normal temperature and coolant level is correct, restricted heater core flow or a failed blend door actuator is most likely preventing heat delivery to the cabin.

Question 5

What does selecting recirculation (MAX A/C) mode accomplish in an HVAC system?

Accepted Answer

Closes the fresh air inlet and recirculates air already inside the cabin

Answer

Recirculation mode closes the outside air intake so the A/C system cools already-conditioned cabin air, achieving maximum cooling efficiency on hot days.

Red Seal Auto Tech 310S Practice Test

Red Seal Auto Tech 310S Practice Test

310S Heating, Ventilation and Air Conditioning (HVAC) 3