Specifications

7-82 Information Manual
Section 7 Cirrus Design
Airplane Description SR20
Description and Operation-Serials 1637 & subsequent
Cabin heating and cooling is provided by mixing ventilation air from the
wing inlet with heated air provided by the muff-type heat exchanger
surrounding the right engine exhaust muffler.The conditioned air is
then forced by ram air pressure or, if option installed, by blower fan into
a distribution manifold which regulates system airflow and vent
selection. Airflow, temperature, and vent selection is accomplished
using the system control panel mounted on the right hand portion of
the instrument panel.
The optional blower fan is powered by 28 VDC supplied through 15-
amp Fan breaker on Main A/C Bus 2.
Airflow Selection
The airflow selector regulates the volume of airflow allowed into the
cabin distribution system through mechanical linkage to a butterfly
valve in the distribution manifold. If option installed, the blower fan is
turned on when the selector dial exceeds the full open position.
Vent Selection
“Conditioned” air from the distribution manifold can be proportioned
and directed to passengers and/or the windshield by manipulating the
cabin vent selector. The selector is mechanically linked to butterfly
valves at the entrances to the windshield diffuser and the cabin floor
ducting. 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 selector is in the far left position, both butterfly valves are
closed providing maximum airflow to the panel and armrest eyeball
outlets.
Rotating the selector a quarter-turn clockwise 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.
Rotating the selector another quarter-turn clockwise opens the
windshield diffuser butterfly valve which permits shared airflow to the
defrosting mechanism and cabin floor outlets.
When the selector is in the far right position, the cabin floor butterfly
valve is closed providing maximum airflow to the windshield diffuser.
March 2010