Deck 9: Case and Duct Systems

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.

Answer 1

True

Question 2

The independent case is used on compact and small cars.

Answer 2

True

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

Answer 3

C

Question 4

A blower motor resistor block may become very hot.

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.

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

Question 7

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

Question 8

If a vacuum reserve tank holds a vacuum for five minutes,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

Question 10

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

Question 11

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

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.

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.

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.

Question 15

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

A) floor
B) defrost
C) panel
D) a and b

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

Question 17

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

Question 19

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

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

Question 21

Technician A says that a liquid antimicrobial deodorizer and disinfectant is used to eliminate odors in duct systems.Technician B says when a musty odor develops the odor causing mold and mildew must be eradicated.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 22

Technician A says a block or ladder diagrams are used to aid in troubleshooting air conditioning duct system faults.Technician B says the use of test lights is not recommended for under dash service.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 23

Electronic actuator motors are being discussed.Technician A says a potentiometer provides a door position signal to the programmer.Technician B says the programmer grounds one side of the energized motor circuit to stop the door movement.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 24

Technician A says the greatest problem in servicing the case and ducts is lack of tools.Technician B says the greatest problem in servicing the case and ducts is lack of service information.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 25

Name the major components of the air distribution system.

Question 26

Dual zone duct systems are being discussed.Technician A says the passenger controls only the passenger side temperature door.Technician B says the driver may be in control of the rear passenger compartment temperature on some systems.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 27

It is necessary to drain the engine coolant before replacing

A) the blower motor.
B) the heater core.
C) the vacuum diaphragm.
D) all of the above.

Question 28

When should the cabin air filter be replaced if the vehicle is operated in dusty or high pollution conditions?

A) Every 3 months or 3,000 miles.
B) Once a year or every 12,000 miles.
C) Every 15,000 miles.
D) Every 30,000 miles.

Question 29

Technician A says a bi-directional mode door actuator may control the mode doors.Technician B says a positive pressure is usually maintained within the passenger compartment.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 30

An inoperative vacuum motor could be caused by all of the following,EXCEPT:

A) defective vacuum switch.
B) door cable misadjustment.
C) leaking reserve tank.
D) kinked hose.

Question 31

Mode door adjustments are being discussed.Technician A says the vacuum motor can be adjusted for motor stroke.Technician B says a cable can be adjusted for full movement of the door.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 32

Technician A says a check valve allows flow in one direction only.Technician B says a check valve blocks flow in one direction only.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 33

Technician A says the heater control valve is found in-line on the heater hose of most vehicles.Technician B says the evaporator may be found inside the engine compartment on some vehicles.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 34

The BILEVEL mode is being discussed.Technician A says air may be directed to the panel and floor in the cooling mode.Technician B says air may be directed to the panel and floor in the heating mode.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 35

Technician A says debris in the fresh air intake can contaminate the refrigerant.Technician B says cleaning the fresh air inlet should be part of a periodic preventative maintenance schedule.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 36

In the MAX cooling position the main source of air is from:

A) defrost air.
B) recirculated air.
C) outside air.
D) vent supply air.

Question 37

What is the sytem called that allows for seperate dirver and front passenger temperature control?

Question 38

Rear heat/cool systems are being discussed.Technician A says this system has its controls in parallel with the front controls.Technician B says some units have the temperature selected by the front controls.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 39

Technician A says the best way to determine the condition of vacuum hoses is by visual inspection.Technician B says a vacuum leak can often be heard.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 40

In the case and duct system the air distribution mode doors may be operated by all of the following Except:

A) Potentiometers
B) Electrically powered motors
C) Cable
D) Vacuum motors

Question 41

Why is it desirable to provide a slightly positive in-vehicle pressure?

Question 42

Why must you be careful not to use undue force when disconnecting heater hoses or the heater core?

Question 43

Explain how the programmer controls the movement of the blend door.

Question 44

How often should the cabin air filter be changed?

Question 45

How may a blend door be controlled?

Question 46

Describe how you would bypass the vacuum system to test an inoperative vacuum motor.

Question 47

Why may the air conditioning compressor be on in the defrost (DEF)position?

Question 48

Why do some systems develop a musty odor?

Question 49

Discuss the airflow when the cooling controls are set to MAX.

Question 50

How does the blend door create the desired in-vehicle temperature?

Question 51

From where does recirculated air come?

Question 52

How are pollen and dust particles stopped from entering the passenger compartment.