HEATING SYSTEM.

TM 5-4120-339-14

3-11.

HEATING SYSTEM.

WARNING

Disconnect the air conditioner from the electrical power before performing the

following procedures on the heating system.

a. Inspection.

(1) Turn selector switch to "OFF" position and disconnect air conditioner from electrical power source.

(2) Refer to figure 3-3 and remove the air conditioner cover and top panel from the unit.

(3) Refer to figures 3-6 and 3-7 and inspect the six heater elements and thermostat for damaged or burned

wiring, loose electrical connections, and other damage which would impair serviceability.

b. Test.

(1) Connect the air conditioner to a 208 volt, 3-phase, 50/60 Hz source of electrical power.

(2) Turn thermostat knob clockwise to its limit.

(3) Turn the selector switch to "LO-HEAT". Refer to figure 3-6 and observe heater elements. Elements 1

through 3 should become hot. Elements 4 through 6 should remain cold.

(4) Turn the selector switch to '"HI-HEAT". Refer to figure 3-6 and observe heater elements. Elements 1

through 6 should become hot.

(5) Turn the selector switch to "OFF" position.

(6) If any heater element fails to function properly during the above test, disconnect electrical power to air

conditioner. Refer to wiring diagram figure 3-8 and check wiring continuity for the improperly functioning heater element

of elements. Repair or replace any defective wiring found.

Replace.

(1) Replace wiring, thermostat or any heater element which shows evidence of damage which would impair

serviceability.

(2) If any heater element fails to function properly during test, and wiring checks OK, refer to step d and

replace defective heater element.

d. Removal and Installation. (See figure 3-7.)

3-18