Airflow Selection; Vent Selection - Cirrus SR22 Pilot Operating Handbook

S 7: A
ECTION IRPLANE AND
E S
NVIRONMENTAL YSTEM
In Air Conditioning mode (optional), R134A refrigerant enters the engine
mounted compressor as a vapor and is pressurized until the heat-laden
vapor reaches a point much hotter than the outside air. The compressor
then pumps the vapor to the condenser where it cools, changes to a liquid,
and passes to the receiver-drier. The receiver-drier's function is to filter,
remove moisture, and ensure a steady flow of liquid refrigerant into the
evaporator through the expansion valve - a temperature controlled
metering valve which regulates the flow of liquid refrigerant to the evapo-
rator. Inside the evaporator, the liquid refrigerant changes state to a gas and
in doing so, absorbs heat. The evaporator then absorbs the heat from the air
passing over the coils and the moisture from the air condenses and is
drained overboard through the belly of the airplane. From the evaporator,
the refrigerant vapor returns to the compressor where the cycle is repeated.
During normal air conditioning operation, ram air from the fresh air intake
flows into the evaporator assembly, is cooled as it passes through the evap-
orator coils, and is then ducted forward to the distribution manifold.

Airflow Selection

The airflow selector on the system control panel regulates the volume of
airflow allowed into the cabin distribution system. When the airflow
selector is moved past the OFF position, an electro-mechanical linkage
actuates a valve in the mixing chamber on the forward firewall to the full
open position. The air is then distributed by either ram air or blower fan to
the distribution manifold mounted to the center, aft side of the firewall. The
airflow system modes are as follows: OFF (ram air), 1 (low fan), 2 (medium
fan), and 3 (high fan).

Vent Selection

Air from the distribution manifold is proportioned and directed to passen-
gers 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 contin-
uous 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.
7-64
S
YSTEMS
C D
IRRUS ESIGN
SR22
P/N 13772-006
Reissue A