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

Selecting between fresh outside air and recirculated cabin air

Answer

Adjusting the blower motor speed

Answer

Directing airflow to specific vents such as floor, dash, or defrost

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

Every 5,000 km

Answer

Every 100,000 km

Answer

It is a lifetime component and never requires replacement

Question 3

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

Accepted Answer

The engine cooling system

Answer

The A/C refrigeration circuit

Answer

The exhaust gas recirculation system

Answer

The power steering hydraulic system

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

The A/C compressor operation

Answer

The engine thermostat operation

Answer

The refrigerant charge level

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

Recirculates refrigerant at a higher rate through the condenser

Answer

Reverses airflow direction through the evaporator to de-ice it

Answer

Bypasses the cabin air filter for maximum airflow

Question 6

A musty odour from the HVAC vents when the A/C is first turned on is typically caused by:

Accepted Answer

Mould or bacterial growth on the evaporator core surface

Answer

Refrigerant contamination in the A/C system

Answer

A burnt blower motor resistor

Answer

Coolant leaking from the heater core into the ductwork

Question 7

Which refrigerant with a very low Global Warming Potential (GWP below 1) is replacing R-134a in newer vehicles under updated environmental regulations?

Accepted Answer

R-1234yf

Answer

R-12

Answer

R-134a

Answer

R-410A