TM 9-2320-273-20
Section XXI CAB HEATING AND VENTILATING SYSTEMS
2-55. INTRODUCTION.
The cab heating and ventilating system are identical in all M915 thru M920 vehicles. This system is
comprised of:
a.
Heater Electrical Control
b.
Heater Water Controls
c.
VentiIating System
2-56. HEATER ELECTRICAL CONTROLS.
1.
2.
3.
4.
ENGINE RUN SWITCH. Controls 12-volt battery power to heater fan switch. When switch is
OFF, fan cannot be actuated.
ClRCUIT BREAKER (CB-4). Protects electrical components of heater fan switch by opening
when load exceeds 20 amps. Automatically recycles until overload is removed.
FAN SWITCH. Four-position switch with three ON positions. Supplies 12-volt battery power
through circuit breaker (CB-4) to motor. Current flow increases as switch is moved from LOW
to MEDIUM to HIGH.
MOTOR. Powers heater fan. Actuated by current from heater fan switch.
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