1. Air Distribution Control
Topics covered in this presentation:
Single and dual distribution assemblies
Blend-air and stacked core re-heat systems
Ducts and louvers
Single & dual systems
ClassAct SRS enabled.

2. Temperature control lever
Introduction
Air distribution systems are used to direct air flow into the passenger compartment.
Airflow is controlled by flaps and mixing doors.
The A/C control panel is mounted in the instrument cluster.
Temperature control lever
The airflow through the heater core is controlled by the temperature selector.
A multi-speed fan is used to change the airflow rate.
Fan control
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3. Air Distribution Section
Typical Heater & A/C Assembly Layout
A single distribution heater system, shown below, is split into three sections.
Air Inlet Section
Plenum Section
Air Distribution Section
Filtered fresh air in
Air to defrost panels
Evaporator
Heater core
Fan
Intake door
Air mix
(blend) door
Floor air out
Recirculated
air in
Air to panel
outlets
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4. Question 1
In a single distribution heater system, the fan is situated in the plenum section. Is this true or false?
Answer True or False.
Correct Answer = F

5. Air Distribution Assembly Location
The air distribution assembly is normally located at the back of the engine compartment, and is fixed to the bulkhead.
Heater and A/C controls
Fan housing
Evaporator housing
Air distribution assembly with heater core
System hoses
Engine
Compressor
Condenser
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6. Question 2 Where is the air distribution assembly normally located?
A) Behind the front grill
B) At the back of the engine compartment
C) Below the engine bulkhead
Correct Answer = B
D) Behind the dashboard

7. Air Flow Through Heater & A/C Assembly
Defrost air out
Filtered fresh air in
Air mix (blend) door
Fan
Intake door
Evaporator
Floor air out
Recirculated
air in
Arrows show the air flow through and around the heater and A/C assembly.
Heater core
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8. Question 3 Where does defrost air normally go to? A) Floor level
B) The windscreen
C) The evaporator
Correct Answer = B
D) The seats

9. Blend-Air Reheat System
The blend-air reheat system works by re-heating and mixing cooled, dried air from the evaporator, using the blend door.
Lines to A/C system
Cold air from
evaporator
Filtered fresh or recirculated air in
Air blend door
Evaporator
Heater core
Hot water lines from engine cooling system to heater core
Hot air from heater core
Blended air to vehicle interior
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10. Stacked Core Reheat System
The stacked core re-heat system works by controlling the temperature of the heater core.
Lines to A/C system
Filtered fresh or recirculated air in
Evaporator
Cold air from evaporator
Heater core
Hot water lines from engine cooling system to heater core
Reheated air to vehicle interior
Heater valve (temperature control)
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11. Question 4
Which is the correct sequence for operations on the air in an a/c system?
A) Cooled, heated, filtered
B) Heated, cooled, filtered
C) Filtered, cooled, heated
Correct Answer = C
D) Heated, filtered, cooled

12. Temperature control lever
Typical Control Panel/Head
The typical panel below contains all the controls and information for the vehicles heating and ventilation.
Temperature control lever
Air conditioning control lever
Air conditioning
on/off switch
Air distribution control lever
Fan control
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13. Control Panel/Head Cable Connections
The control levers and switches are connected to the distribution controls behind the control panel.
Air conditioning
control lever
Temperature control cable
Temperature control lever
Fan control connector
Air distribution
control cable
Air conditioning on/off switch connector
Air conditioning
control cable
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14. Heating System Inlets and Outlets
Inlet and outlet ducts are used to recycle and change the air within the passenger compartment.
Windscreen defroster nozzle
Side window outlet
Filtered fresh air in
Side window outlet
Instrument panel outlets
Floor outlets
Instrument panel outlets
Re-circulated air in
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15. Louver Construction
Outlet louvers are used to control and direct heating and ventilation air flow into the passenger compartment.
Air door
control wheel
Air control door
Louver housing
Louver
Louver direction control
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16. Front & Rear Passenger Compartment Ducts
Compartment ducts are used to direct heating and ventilation air around the vehicle, luxury vehicles have very complex systems.
Front compartment ducts
Defroster outlets
Side window outlet
Instrument panel
outlets
Side window outlet
Rear compartment ducts
Rear compartment outlets
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17. Question 5
What is the name of the parts of the vehicle used to control the flow of air into the passenger compartment?
A) Duct
B) Louver
C) Outlet
Correct Answer = B
D) Nozzle

18. Dual-Zone Distribution System
Dual-zone heating and ventilation distribution systems allow for personal settings, when selecting heating and ventilation temperatures.
Driver defrost door
Driver windscreen
outlet
Filtered fresh
air in
Driver floor outlets
Driver air mix (blend) door
Driver mode door
Driver
panel
outlets
Heater core
Evaporator
Passenger
windscreen
outlet
Passenger
panel outlets
Fan
Passenger
defrost door
Passenger air mix (blend) door
Passenger
floor outlets
Passenger mode door
Recirculated
air in
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19. Summary You should now be aware of:
Single and dual distribution assemblies
Blend-air and stacked core re-heat systems
Ducts and louvers
Single & dual systems
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