Evaporator Fan Motors (B3A and B3B)

TM 5-4120-393-14

4-56. Evaporator Fan Motors (B3A and B3B)

This task covers:

a. Removal

c. Testing

b. Inspection

d. Installation

Initial setup.

Tools:

Tool kit, service, refrigeration unit NSN 5180-00-596-1474

Personnel: 2

Materials: Rags NSN 7920-00-205-1711

Equipment condition:

1. Turn unit power off at power source. If there is a chance that it will be turned on, also disconnect power cable

to air conditioner.

2. Remove top panel. See para 4-25.

3. Remove conditioned air filters. See para 4-30.

4. Remove conditioned air inlet grilles. See para 4-22.

General Safety Instructions:

WARNING

Disconnect input power to the air conditioner before performing any internal

maintenance. Voltages used can KILL. Shutting the unit off at the control panel

does not disconnect unit power.

TESTING (INSTALLED)

Check to see that power has been disconnected.

Check motor for rotational freedom by spinning fan. If there is any stiffness or binding, contact Intermediate Direct

Support Maintenance.

Check motor bearing for lateral or end play. If there is excessive lateral or end play, contact Intermediate Direct

Support Maintenance.

Electrically test motor as follows.

(a) Disconnect motor cable connector.

(b) Use a multimeter set on lowest OHMS scale to check continuity between A and B, A and C, and B and C in

connector. If there is no continuity between any pairs of pins, the motor winding is open. Replace motor.

and the motor housing. If there is continuity between any pin and the motor housing, the motor winding is

shorted, replace motor.

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