mature relays. compressor
relay. time delay, circuit breaker, rectifier, termi-
nal boards, and fuse holders and fuses.
Figure 3-12. Junction box, removal and installation.
(1) Refer to paragraph 3-26 and remove or
disconnect the control panel.
Note. Remove the circuit breaker reset knob prior
to removing the junction box.
(2) Refer to figure 3-12 and remove the
c. Installation. Installation is the reverse of re-
a. Phase Sequence Relay.
(1) General. The phase sequence relay, lo-
cated in the center right corner of the, junction
box, prevents operation of the compressor unless
the phase sequence is correct. This measures proper
rotation of the compressor motor and prevents
terminals A, B, and C of phase sequence relay
(K6). If not correct, verify correct external
power has been connected.
(b) Check voltage between terminal 1 of
fuse holder (XF1) and junction box ground
(El). 120 (±10) volts should be indicated, or
relay is defective and should be replaced.
(a) Refer to figure 3-4 and remove the
lower front access cover.
(b) Remove cover from junction box (fig.
(c) Refer to figure 3-13 and remove the
(4) Installation. Installation is the reverse
b. Armature Relays.
(1) General. The armature relays (K4 and
K5) control electrical power to the fan as called
for by the positioning of the two-speed fan
switch. When the fan switch is in the LO-SPEED
position, an increase in compressor discharge
pressure to 400 (±16) psig will close the nor-
mally open pressure switch (S3) and cause the
armature relay (K4) to close, placing the fan
motor in III-SPEED. When the discharge pres-
sure drops to
350 (±16) psig, the pressure
(a) Apply 208 volts, 60 Hertz, 3-phase
(ABC) ac electrical power to the air conditioner
Check for 208 volts, 60 Hertz, 3-phase, power at