Textron Cessna C172S PIM, Pilot Operating Handbook

Page: 287 / 322

CESSNA SECTION 7
MODEL 172S NAV III AIRPLANE AND SYSTEM DESCRIPTION
GFC 700 AFCS
U.S.
AVIONICS SUPPORT EQUIPMENT
Avionics cooling fans, antennas, microphone and headset provisions,
power converter and static discharge wicks support the operation of the
avionics equipment installations.
AVIONICS COOLING FANS
Four DC electric fans provide forced air and ambient air circulation
cooling for the G1000 avionics equipment. A single fan in the tailcone
provides forced air cooling to the integrated avionics units and to the
transponder. A fan located forward of the instrument panel removes air
from between the firewall bulkhead and instrument panel, directing the
warm air up at the inside of the windshield. Two additional fans blow air
directly onto the heat sinks located on the forward sides of the PFD and
MFD.
Power is provided to these fans when the MASTER (BAT) switch and
the AVIONICS (BUS 1 and BUS 2) switch are all ON.
NOTE
None of the cooling fans will operate when the essential
bus avionics equipment is being powered by the standby
battery.
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172SPHBUS-00 7-73