FREE 310T HVAC and Cab Systems Questions and Answers

Question 1

A technician connects A/C manifold gauges to a truck and observes that both the high-side and low-side pressures are significantly lower than normal for the current ambient temperature.
The compressor clutch is engaged.
What is the most likely cause of these readings?

Accepted Answer

The system has a low refrigerant charge.

Answer

The system is overcharged with refrigerant.

Answer

There is a restriction in the high side of the system.

Answer

The condenser is clogged or has poor airflow.

Question 2

Which type of refrigerant oil is specified by most manufacturers for use in heavy-duty truck A/C systems charged with R-134a?

Accepted Answer

PAG (Polyalkylene Glycol) Oil

Answer

Mineral Oil

Answer

POE (Polyol Ester) Oil

Answer

Alkylbenzene Oil

Question 3

In a truck's HVAC system that does not use a heater control valve, which component is responsible for regulating the outlet air temperature?

Accepted Answer

The temperature blend door

Answer

The blower motor resistor

Answer

The thermostatic expansion valve

Answer

The A/C cycling switch

Question 4

A driver reports that their truck's Automatic Temperature Control (ATC) system is stuck on the highest heat setting and will not switch to cool air. A diagnostic scan reveals a fault for the 'Temperature Blend Door Actuator'. This fault indicates a problem with the component that:

Accepted Answer

physically moves the door that mixes hot and cold air.

Answer

controls the speed of the blower motor.

Answer

meters refrigerant flow into the evaporator.

Answer

directs airflow to the floor, vent, or defrost outlets.

Question 5

What is the primary purpose of an air-ride cab suspension system on a heavy-duty truck?

Accepted Answer

To improve driver comfort by isolating the cab from chassis vibrations.

Answer

To provide adjustable ride height for the entire truck.

Answer

To increase the vehicle's overall load-carrying capacity.

Answer

To stiffen the suspension during high-speed cornering.

Question 6

According to Canadian federal regulations, what is the mandatory procedure a technician must follow before opening an A/C system containing HFC refrigerants like R-134a for service?

Accepted Answer

Use certified recovery equipment to capture the refrigerant.

Answer

Vent the refrigerant slowly into a container of oil.

Answer

Flush the system with nitrogen to purge the refrigerant.

Answer

Neutralize the refrigerant with an approved chemical agent.

A technician connects A/C manifold gauges to a truck and observes that both the high-side and low-side pressures are significantly lower than normal for the current ambient temperature.The compressor clutch is engaged.What is the most likely cause of these readings?

A technician connects A/C manifold gauges to a truck and observes that both the high-side and low-side pressures are significantly lower than normal for the current ambient temperature.
The compressor clutch is engaged.
What is the most likely cause of these readings?