Section XII. MAINTENANCE OF T H E ELECTRICAL SYSTEM

Section XII. MAINTENANCE OF T H E ELECTRICAL SYSTEM

non box by removing the four screws which secure

4-35.

General

it to the top of the junction box.

T h e heart of the air conditioner electrical system is

(3) Remove the knob from the thermostat by

the junction box and control panel which are

loosening the two set screws with a .050 Hexagon

mounted behind the front access panel. Com-

Head wrench.

ponents not integral to these two electrical boxes

( 4 ) Remove the back panel of the control panel

are the fan motor and compressor, start/run

b y removing the four nuts and screws which secure

capacitors, electric heating elements, fan speed

it to the control panel.

relay, heater thermostat, solenoid valve coils, and

d. Complete Disconnection of Junction Box.

outside air thermostat, In addition to these com-

(1) Follow the steps outlined in Paragraph 4-

ponents there are three wiring harnesses in the air

35-b to partially remove the junction box.

conditioner to interconnect them to the junction

( 2 ) Disconnect the two electrical connectors on

b o x and control panel, It is necessary to remove the

the back left side of the junction box and the

junction box and control panels from the air

connector on the, left side of the control panel.

conditioner to service most of the components

( 3 ) Remove the hex head screw which secures

integral to them,

the front left corner of the casing to the bottom

4-36. Removal, Service and Installation of the

panel of the air conditioner and remove the elec-

Junction Box and Control Panel

trical ground wire.

a . General. It is necessary to completely remove

( 4 ) Remove the junction box and control panel

the junction box and control panel for access to

from the air conditioner.

some components located in the lower portion of

e . Servicing. Servicing consists of test, inspection

the air conditioner. The electrical connections

or replacement of defective electrical components

(three electrical connectors and the electrical

included in the junction box or control panel. All

ground wire) do not have to be disconnected for

gaskets and insulation should be inspected for

most servicing of the junction box and control

defects and proper adhesion to the metal surfaces

panel.

and re-glued or replaced as required. Check the

b. Removal of Junction Box for Servicing and

four captive screws on the junction box cover and

Replacing Components.

t h e four which secure the junction box to the right

( 1 ) Remove the front access panel (para 4-12).

and left side mounting brackets to insure that the

(2) Loosen the four screws which secure the

retaining washers are in place to retain the screws

junction box to its right and left hand mounting

in their respective mounting holes. Wiring har-

brackets.

nesses and wire leads should be checked to insure

( 3 ) Loosen the two clamps located on the right

t h a t all connections are tight, the wire insulation is

end of the junction box which secure the circuit

s e r v i c e a b l e and that the wiring is routed and tied to

b r e a k e r actuator cable. Remove the end fitting core

p r e v e n t chafing on sharp edges or interference with

from the end of the actuator cable and slide the

internal components.

cable up out of the two clamps which held it.

f Installation. Installation shall be in the reverse

(4) Remove the intake air grille (para 4-13)

order of removal.

and the air filter (para 4-21). Remove the clamp

4-37. Circuit Breaker

which secures the thermostat sensing bulb to the

a. Function. This is a two pole breaker with a

c a s e by removing the screw which secures it to the

mechanically interlocked auxiliary switch. The

casing.

circuit breaker opens if there is excessive current

(5) Slide the thermostat bulb through the

draw by the compressor or the electric heating

g r o m m e t located in the partition above the junction

elements. The auxiliary switch opens when the

b o x . Take care to insure that the capillary tube does

main poles open and de-energizes the low voltage

not become kinked or broken.

control system of the air conditioner.

(6) Remove the front cover from the junction

b. T e s t i n g . Remove the junction box from the air

box by loosening the four captive screws which

conditioner (para 4-36-b). Disconnect and tag all

secure it to the front flanges of the junction box.

w i r e leads. Check for continuity between each pair

(7) Slip the junction box with the control

o f wire terminals when the circuit breaker is closed

module attached out of the air conditioner casing.

and open circuit when open. Check for insulation

c. Removal of Control Panel for Servicing.

resistance between the three electrical circuits.

( 1 ) Follow the steps outlined in Paragraph 4-

L a c k of continuity when closed, open circuit when

3 5 - b to r e m o v e t h e j u n c t i o n b o x .

open or low insulation resistance between circuits

(2) Remove the control panel from the junc-

4-12