Vent Selection; Temperature Selection - Cirrus SR20 Pilot Operating Handbook

Section 7 Cirrus Design
Airplane and Systems Description SR20

Vent Selection

Air from the distribution manifold is proportioned and directed to
passengers and/or the windshield by pressing the cabin vent selector
buttons which electrically actuate butterfly valves at the entrances to
the windshield diffuser and the cabin floor ducting.
When the Temperature Selector is in the blue "cool" zone, there is
continuous airflow to the panel and armrest eyeball outlets. Each
occupant can control the flow rate from 'off' to maximum by rotating the
nozzle.
When the Panel selector button is pushed, both butterfly valves are
closed providing maximum airflow to the instrument panel and armrest
eyeball outlets.
Pressing the Panel-Foot selector button opens the cabin floor butterfly
valve allowing airflow to the rear seat foot warmer diffusers and the
front seat outlets mounted to the underside of each kickplate.
Selecting Panel-Foot-Windshield button opens the windshield diffuser
butterfly valve which permits shared airflow to the defrosting
mechanism and cabin floor outlets.
When the Windshield selector button is pushed the cabin floor butterfly
valve is closed providing maximum airflow to the windshield diffuser.

Temperature Selection

The temperature selector is electrically linked to the hot and cold air
valves. Rotating the selector simultaneously opens and closes the two
valves, permitting hot and cold air to mix and enter the distribution
system. Rotating the selector clockwise, permits warmer air to enter
the system - counterclockwise, cooler air.
On airplane with the optional Air Conditioning System installed, when
the air conditioning button (snowflake) is pushed, the valve on the
firewall completely closes and the air conditioner is activated. When
recirculation button is pushed, the fresh air valve completely closes
and cabin air is recirculated to provide for maximum air conditioning
operation. When the air conditioning system is on and the temperature
selector is rotated to the full cool position, recirculating mode can be
activated to provide maximum cabin cooling. Air conditioning or
recirculating mode is not available when the airflow fan selector is in
the "0" position. Recirculating mode is not available unless the air
conditioning system is operating.
7-74 P/N 21399-004
Revision A1