TM 9-4120-357-14
WARNING
Disconnect power from the air conditioner before performing maintenance work
on the electrical system. The voltages used can be lethal.
Allow heaters to cool before touching. Severe burns can result from touching hot heaters.
b. Removal. Remove the thermostatic switch (7, figure 4-14) from the bracket on the rear surface of the heater
support assembly (8), by disconnecting three wires and removing two screws, rivets and washers from the mounting
flange.
c. Inspection/Test. Inspect the heater thermostat for obvious physical damage. Test as follows:
(1) Tape a thermometer on the junction of a thermocouple to the body of the thermostat.
(3) Gradually apply heat to the thermostat, using a heat lamp or other convenient source, and observe the conti-
nuity tester. Continuity should exist until the temperature shown by the thermometer or thermocouple reaches 185-203
F
(85-95 ), then drop out.
C
(4) Remove the heat source and observe the continuity tester as the thermostat cools. Continuity should be re-
established at 125-158 (52-700C).
F
(5) Disconnect the ohmmeter or continuity tester from one of the thermostat wires, and connect it to the remain-
ing wires. Repeat steps (3) and (4). Replace thermostat if it does not meet continuity requirements.
d. Installation. Position the thermostatic switch (7, figure 4-14) in hole in bracket, and secure with two screws,
washers and nuts. Connect wires to terminals of heating elements (10).
e. Final Assembly. Assemble the air conditioner as follows:
(1) Position the top panel on the unit. Secure it with 31 screws through the top and rear flange.
Section XIV. MAINTENANCE OF FANS AND MOTORS
4-43. General.
Airflow through the condenser is provided by motor-drive axial fan. The condenser fan is driven by a horsepower (2.98
kw), 208-volt, 50/60 Hz, 3-phase, 1725 rpm motor. The centrifugal evaporator blowers are driven by a 1.25 horsepower
(0.9325 kw), 208-volt, 50/60 Hz, 3-phase, 3450 rpm, doubleshaft motor.
4-44 Maintenance of Evaporator Fan and Motor.
a. Access. Obtain access to the evaporator fan and motor assembly as directed in the following steps:
WARNING
Extreme caution should be exercised whenever unit must be operated with
protective panels or grillwork removed, as evaporator fans are rotating at 3450
RPM and condenser fan is rotating at 1725 RPM.
(1) Remove 16 screws and washers from the frame of the evaporator discharge grille. Remove the grille.
(2) Remove 12 screws and washers from each evaporator intake grille. Remove both grilles.
(3) Remove 31 screws from the top and rear flange of the top panel. Remove the panel.
4-48
