Heater, Defroster, and Ventilation Mechanisms.

TROUBLESHOOTING THE HMMWV - OD1616 - LESSON 1/TASK 2

(10) Electric Horn.

A single electric horn is mounted under the

hood, forward facing, near the front of the vehicle.

It is a

standard military 24 Volt horn, activated by a horn button in the hub

of the steering wheel.

(11) Windshield Wiper/Washer.

The HMMWV includes a windshield

wiper/washer system to maintain a clear field of vision through the

windshield. This system consists of a two-speed electric motor, two

wiper blades, blade linkage, washer reservoir, two washer jets,

connecting hoses, and a motor.

The motor is located inside the

vehicle at the top of the windshield and drives the blade linkage

inside the windshield header.

Dual ten inch blades are actuated by

the linkage and pivot from the top of the windshield frame.

The

blades operate in unison and return to a PARK position at the right

side of the "wipe pattern" when the wiper switch is turned off.

Windshield washing is accomplished through two jets on the cowl below

the windshield. The fluid is contained in a reservoir located in the

engine compartment.

Always use an approved washing solution or

water; NEVER engine anti-freeze.

(12) Heater, Defroster, and Ventilation Mechanisms.

The heater,

defroster, and ventilation mechanisms usually are combined into one

unit to comprise a complete system.

The unit, which is called a

heater unit, consists of a chambered box containing a heater core and

control doors to allow the operator to select the desired mode of

operation. The outside of the box contains openings for outside air

intake, so that fresh air can be recirculated. The box also has an

interior air intake, so that inside air can be recirculated;

defroster outlets, so that forced air can be provided to clear the

windshield; heater outlets, so that heated air can be provided,

usually at floor level; and, ventilation outlets so that air can be

forced into the passenger compartment at instrument panel level. An

electric blower motor also is combined with this unit to provide air

movement.

(a) Heater Core.

The main component of the HMMWV's heater

system is the heater core.

The heater core is the component that

transfers heat from the engine coolant to the passenger compartment.

Its construction is similar to that of a radiator, except it is on a

much smaller