ARMY TM 9-4120-380-14
NAVY EE-000-BA-MMA-010/7053-AC
AIR FORCE TO 35E9-136-21
Section VI. UNIT MAINTENANCE PROCEDURES - Continued
Paragraph
Title
Page
Condenser Fan and Housing Assembly .........................................................................................
Condenser Motor (B3) ...................................................................................................................
Electric Heaters (HR 1 and HR2) ...................................................................................................
Heat Limit Switches (S9 and S10) .................................................................................................
Thermostat (S2) ............................................................................................................................
Airflow filter Switch (S3) ................................................................................................................
Heat Fault Thermostat (S8) ...........................................................................................................
Crankcase Heater (HR3)................................................................................................................
Solenoid Valves (L1 and L2) Coil...................................................................................................
Condenser Coil ..............................................................................................................................
4-130
Evaporator Coil .............................................................................................................................
Drain Area .....................................................................................................................................
4-134
4.17
GENERAL. This section contains functional description and maintenance procedures which are authorized to
Unit Maintenance (O) by the Maintenance Allocation Chart (MAC), Appendix B and Source Maintenance and
Recoverability (SMR) coded items. Each paragraph covers a complete maintenance procedure but may require other
tasks to be included (i.e. initial setups references and follow-on procedures). Perform procedures/tasks in designated
order.
4.18
FUNCTIONAL DESCRIPTION. The air conditioner control circuits are described in the following paragraphs. It
is very important for the technician to note that even when the air conditioner mode switch is positioned to OFF and
circuit breakers CB1 and CB2 are open, live voltage is available throughout the air conditioner and at least one input
phase C circuit is complete to neutral. (See fig 4-12 and fig. FO-2.).
4.18 1 When 208 V, 3-phase AC power is applied to the air conditioner through terminal board (TB1) the following
circuits are enabled:
a. Input phases A B and C are applied to one side of the relay contacts of compressor contactor (K1) evaporator
fan motor contactor (K2) condenser fan motor contactor (K3) first stage heater contactor (K4), second stage
heater contactor (K5) and to the coil of the phase relay (K6).
b. In addition, phase B is also routed through the compressor crankcase heater (HR3) and to the line side of the
crankcase heater circuit breaker (CB2).
c. Phase C is also applied to the load side of the crankcase heater circuit breaker (CB2) and the line side of the
control circuit breaker (CB1), illuminates the POWER ON indicator (DS1 ) and completes the circuit at the neutral
side of the compressor contactor (K1) coil.
4.18.2 With the PRIME UNIT SELECT switch (S11) set to PRIMARY, phase C input power is also routed through
contacts of the latching relay (K11), to contacts of the compressor and condenser fan motor time delay relays (TR1 and
TR2), to the center contacts of the thermostat (S2) and the MODE SELECT switch (S1) and is present on the remote
status terminal board (TB2).
4.18.3 When the PRIME UNIT SELECT switch (S11) is set to BACKUP electrical power is not applied to the operating
modes control circuits unless the primary air conditioner in a dual configuration has failed. This function is described in a
subsequent subparagraph.
4-30
