Question 1

Due to the radiant heat of the sun,the temperature of the interior surfaces can range from 50°-100°F above ambient air temperatures.

Accepted Answer

The radiant heat of the sun can cause interior surfaces to become much hotter than the ambient air temperature, resulting in temperatures ranging from 50-100°F above the outside temperature.

Question 2

The independent case is used on compact and small cars.

Accepted Answer

The independent case is often used on compact and small cars because these cars typically have less weight and do not require as much torque strength as larger vehicles.

Question 3

Technician A says mode doors may be electrically operated.Technician B says mode doors may be vacuum operated.Who is correct? A) Technician A only B) Technician B only C) Both A and B D) Neither A nor B

Accepted Answer

Mode doors can be either electrically or vacuum operated depending on the design of the HVAC system. Therefore, both Technician A and Technician B are correct.

Question 4

A blower motor resistor block may become very hot.

Accepted Answer

The blower motor resistor block controls the speed of the fan in a heating, ventilation, and air conditioning (HVAC) system. As it regulates the voltage that reaches the blower motor, it may become very hot due to resistance and electrical current flowing through it.

Question 5

All of the following statements about a typical system set to MAX (maximum)cooling are true,EXCEPT:
A) The compressor clutch is engaged.
B) The blower is running.
C) The outside/recirculate air door is opened to outside air.
D) Airflow is from inside the car, through the evaporator and heater core, and out through the panel registers.

Accepted Answer

When a typical system is set to MAX cooling, the outside/recirculate air door is closed to recirculate the air within the car to maximize cooling efficiency. Therefore, statement C is false. All the other statements are true.

Question 6

A customer complains of the passenger compartment temperature always being too hot,cold or not changing as the temperature range is changed on the control panel.On an electronic mode door actuator (motor)system all of the following could cause this problem Except:
A) Mode door moving too freely
B) Faulty actuator
C) Open or shorted wire
D) Faulty potentiometer

Accepted Answer

If the mode door is moving too freely, it may cause excessive air flow to a particular area, but it would not cause the passenger compartment temperature to always be too hot, cold, or not changing with the temperature range. Faulty actuator, open or shorted wire, and faulty potentiometer could all cause such a problem.

Question 7

In the maximum cooling mode,all air enters from outside the vehicle.

Accepted Answer

In the maximum cooling mode, most vehicles recirculate the already cooled air inside the vehicle instead of pulling in hot outside air, to cool the interior more efficiently.

Question 8

If a vacuum reserve tank holds a vacuum for five minutes,the tank is probably good.

Accepted Answer

If a vacuum reserve tank holds a vacuum for five minutes, it means that it can maintain the vacuum pressure for a reasonable amount of time and is functioning properly. Therefore, the tank is probably good.

Question 9

Technician A says a semiautomatic temperature control (SATC)system is operated by engine vacuum.Technician B says an automatic temperature control (ATC)system is operated by a digital microprocessor.Who is correct? A) Technician A only B) Technician B only C) Both A and B D) Neither A nor B

Accepted Answer

Technician B is correct. An automatic temperature control system (ATC) is operated by a digital microprocessor, while a semiautomatic temperature control system is not necessarily operated by engine vacuum - it could also be operated by a cable or other mechanical means.

Question 10

The blower can be installed upstream or downstream of the other components.

Accepted Answer

It is possible to install the blower upstream or downstream of other components in a system.

Question 11

On most systems all incoming air passes through the heater core.

Accepted Answer

Not all systems route all incoming air through the heater core; some systems have a blend door that allows air to bypass the heater core for temperature control.

Question 12

If a musty odor develops and becomes very pronounced when the HVAC system is first turned on,the case should be washed out with a garden hose.

Accepted Answer

A musty odor when the HVAC system is first turned on usually indicates the presence of mold or mildew. Washing out the case with a garden hose will not effectively address this issue as it only cleans the exterior. A professional HVAC technician should be called to properly diagnose and address any mold or mildew growth in the system.

Question 13

During normal air conditioning system operation,system mode doors are
A) fully opened.
B) fully closed.
C) partially closed.
D) all of the above, depending on the mode selected.

Accepted Answer

The system mode doors can be fully opened, fully closed or partially closed depending on the mode selected. For example, in the cooling mode, the evaporator air door and the recirculation air door would be fully opened, while the heater air door and fresh air door would be fully closed. In other modes like defrost or vent, some doors may be partially closed to control the airflow. Therefore, option D is the best choice.

Question 14

An odor emitting from the case and duct system may be caused by all of the following,Except:
A) Refrigerant gas leak.
B) Mold and mildew.
C) Refrigerant oil leak.
D) A leaking heater core.

Accepted Answer

Refrigerant gas is typically odorless, so it would not cause an odor to emit from the case and duct system.

Question 15

In the MIX/BILEVEL position,conditioned air is delivered to the ____ outlet.
A) floor
B) defrost
C) panel
D) a and b

Accepted Answer

In the MIX/BILEVEL position, conditioned air is delivered to both the floor and defrost outlets. Therefore, the best choice is D, which includes both options.

Question 16

A customer complains that air flow shifts from the dash vents to the floor vents during hard acceleration.Technician A says that it could be caused by a misadjusted blend air door.Technician B says this could be caused by a leaking vacuum supplu line.Who is correct? A) Technician A only B) Technician B only C) Both A and B D) Neither A nor B

Accepted Answer

The issue described is typically related to a vacuum problem in the HVAC system, as vacuum is used to control the position of the doors that direct airflow. A leaking vacuum supply line would reduce vacuum pressure, causing the system to default to another position (like the floor vents) during conditions that lower vacuum pressure further, such as hard acceleration. A misadjusted blend air door would affect the temperature of the air, not the direction of airflow.

Question 17

Under normal operation,most of the moisture that may build up in the evaporator case will drain out of the case drain.

Accepted Answer

The evaporator case is designed to allow moisture to drain out of it to prevent build-up. Therefore, under normal operation, most of the moisture that may build up in the evaporator case will drain out through the case drain.

Question 18

It is necessary to drain the engine coolant before replacing
A) The heater core.
B) The blower motor.
C) The vacuum diaphragm.
D) All of the above.

Accepted Answer

The answer of It is necessary to drain the engine...

Question 19

Even in the MAX A/C mode,some systems provide for up to 50 percent fresh air.

Accepted Answer

The answer of Even in the MAX A/C mode,some systems...

Question 20

When the A/C system is first turned on a foul smell comes out of the duct system.Technician A says that evaporaor icing could be the cause.Technician B says that mold forming in the evaporator case and on the core could be the cause.Who is correct?
A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Accepted Answer

Mold forming in the evaporator case and on the core is a common cause of foul smells when the A/C system is first turned on. Evaporator icing does not typically cause odors.

Quiz 9: Case and Duct Systems

Due to the radiant heat of the sun,the temperature of the interior surfaces can range from 50°-100°F above ambient air temperatures.

The independent case is used on compact and small cars.

Technician A says mode doors may be electrically operated.Technician B says mode doors may be vacuum operated.Who is correct?

A blower motor resistor block may become very hot.

All of the following statements about a typical system set to MAX (maximum) cooling are true,EXCEPT:

A customer complains of the passenger compartment temperature always being too hot,cold or not changing as the temperature range is changed on the control panel.On an electronic mode door actuator (motor) system all of the following could cause this problem Except:

In the maximum cooling mode,all air enters from outside the vehicle.

If a vacuum reserve tank holds a vacuum for five minutes,the tank is probably good.

Technician A says a semiautomatic temperature control (SATC) system is operated by engine vacuum.Technician B says an automatic temperature control (ATC) system is operated by a digital microprocessor.Who is correct?

The blower can be installed upstream or downstream of the other components.

On most systems all incoming air passes through the heater core.

If a musty odor develops and becomes very pronounced when the HVAC system is first turned on,the case should be washed out with a garden hose.

During normal air conditioning system operation,system mode doors are

An odor emitting from the case and duct system may be caused by all of the following,Except:

In the MIX/BILEVEL position,conditioned air is delivered to the ____ outlet.

A customer complains that air flow shifts from the dash vents to the floor vents during hard acceleration.Technician A says that it could be caused by a misadjusted blend air door.Technician B says this could be caused by a leaking vacuum supplu line.Who is correct?

Under normal operation,most of the moisture that may build up in the evaporator case will drain out of the case drain.

It is necessary to drain the engine coolant before replacing

Even in the MAX A/C mode,some systems provide for up to 50 percent fresh air.

When the A/C system is first turned on a foul smell comes out of the duct system.Technician A says that evaporaor icing could be the cause.Technician B says that mold forming in the evaporator case and on the core could be the cause.Who is correct?