Chapter 6. REPAIR INSTRUCTIONS - TM-5-4120-337-140065

CHAPTER

REPAIR INSTRUCTIONS

Section

CONTROL

MODULE

REPAIR

6-2. Junction Box

6-1.

Control Panel

a. General. The junction box is tile electrical

a. General. The control panel contains the

nerve center of the air conditioner. Contained

electrical switches that enable the operator to select

herein are the relays, fuses, transformer, terminal

the appropriate method of heating, cooling or

b o a r d s , circuit breaker and rectifier. This box may

v e n t i l a t i o n required at a given time. This panel may

b e disassembled, components inspected, tested, and

be disassembled. inspected and defective parts

defective parts replaced as required.

replaced as required.

b. Disassembly.

(1) Remove the front access panel.

(1) Remove the front access panel and the

( 2 ) R e m o v e t h e c o n t r o l p a n e l f r o m the

i n t a k e grille by removing the screws attaching them

junction box top as described in paragraph 6-1.

t o the casing. Remove the air filter. Disconnect the

(3) Disconnect the two electrical connectors

temperature sensing bulb by removing screw and

from the rear of the junction box.

c l a m p and push it down through the grommet until

(4) Remove the circuit breaker re-set cable

i t is out of the way.

e n d fitting. Remove the two clamps which the cable

( 2 ) Disconnect the electrical power connect to

to the right end of the junction box by removing two

the control panel.

screws and spacers.

(3) Remove the four screws that secure the

control panel to the top of the junction box.

( 5 ) Remove the ground lead from the back of

the junction box by removing the screw, washers

(4) Remove the knobs from the front of the

a n d nut. Remove the other end of the lead from the

panel by loosening the setscrews. Remove nut and

casing ground by removing the screw and washer

washer which secure the temperature control

which secure the casing to the base panel in the

thermostat to the front of the control panel.

lower left front corner of the air conditioner.

(5) Remove the rear panel by removing four

(6) Loosen two screws on each side of box and

screws and nuts.

remove junction box assembly.

(6) Remove four screws and washers securing

the electrical connector and wiring harness to the

( 7 ) Remove the front cover of the junction box

by loosening the four screws.

left end of the control panel. First disconnect

wiring harness leads after tagging them. Remove

(8) Disconnect and tag the leads to circuit

and tag the three separate electrical leads.

b r e a k e r . Remove the six screws holding the circuit

breaker and cover plate and remove the circuit

(7) Disconnect ground wire lead by removing

screw, washers and nut.

breaker and circuit breaker cover from the right

end of the junction box.

(8) Remove the temperature control by

r e m o v i n g four screws and nuts from the rear panel.

(9) Remove the circuit breaker reset lever by

(9) Remove the fan speed switch and selector

removing the pin in the circuit breaker throw bar.

switch by removing the nuts and washers which

(10) Remove the two fuses from the fuse

secure them to the front of the control panel.

holders on the left end of the junction box.

c. Inspection. Inspect all components of control

(11) Disconnect and tag the leads from the

p a n e l assembly for cracks, breaks, and dirt or other

transformer. Remove the capacitor from the two

foreign substances.

output terminals X1 and X2 of the transformer.

d. Cleaning. Clean all parts in dry cleaning

R e m o v e the transformer by removing the four nuts

solvent, Federal Specification P-S-661, Use a stiff

securing it to the junction box top panel.

bristle brush to brush away dirt, scale, and other

(12) Disconnect and tag all electrical leads,

(13) Remove time delay mounting bracket by

foreign matter. Use low pressure, dry, compressed

r e m o v i n g three screws. Remove the two time delay

air to blow cleaned components dry.

relays by removing four screws and nuts.

e. Repair or Replacement. Replace all defective

(14) Remove rectifier by removing nut and

parts.

w a h e r from the left of the top panel of the junction

f. Reassembly.

Reassembly shall be in the

box.

r e v e r s e order of disassembly, Make sure all tagged

wires are connected to the proper terminals.

6-1