Transformer - TM-5-4120-337-140045

check for a high insulation resistance between the

indicates that the circuit breaker is defective and

four terminals and case of the transformer. Check

should be replaced.

for continuity between terminals H1 and H2 and

c. Removal. Remove the six screws which

X1 and X2. Any low insulation resistance or lack of

secure the circuit breaker and metal cover to the

continuity

indicates that the transformer is

right end of the junction box. Remove the plastic

defective and must be replaced.

c i r c u i t breaker cover. Drive the steel pin out of the

c. Removal. Remove the four hexagon nuts,

circuit breaker throw bar and remove the actuator

eight flat washers and four lock washers which

arm. Remove the circuit breaker from the junction

box.

secure the transformer to the top right side of the

d. Installation. Installation shall be in the

junction box after removing and tagging four wire

reverse order of removal. When installing a new

leads and capacitor. Remove the transformer.

c i r c u i t breaker, discard the spacer on the throw bar

d. Installation. Installation shall be in the

to allow installation of the actuator arm.

reverse order of removal. Insure that the gasket

u n d e r the transformer is in serviceable condition. Be

4-38. Transformer

sure that the capacitor is re-installed across the two

a. Function. The transformer steps down the

output terminals X1 and X2 of the transformer.

1 1 5 volt input voltage to 30 volts for operation of

4-39. Rectifier

all electrical controls.

b . Testing. Remove the junction box from the air

a. Function. The rectifier is used to rectify the

conditioner (para 4-36 b). Check the output ter-

AC current to provide DC power to operate the

m i n a l s X1 and X2 for a voltage of 29 to 31 volts

control circuit.

with an air conditioner input voltage of 115 volts

b. Testing. Remove the junction box from the air

a n d with the mode selector switch set to any of the

c o n d i t i o n e r ( p a r a 4 - 3 6 b). T a g a n d d i s c o n n e c t t h e .

four operating positions. Disconnect all power to

four wire leads from the rectifier. Using an ohm

the air conditioner and remove and tag the four

meter measure the resistance between terminals as

leads to the transformer. Remove the capacitor

follows:

connected across the two output terminals and

Terminal

Resistance

Ohmmeter Probe

Terminal

Low

High

Resistances not in accordance with the above test

indicate an open circuit. Energize the control

indicate a defective rectifier.

circuit and again measure the resistance across

c. R e m o v a l . R e m o v e t h e n u t a n d l o c k w a s h e r

contacts 2 and 3. The resistance should again be

w h i c h secure the rectifier to the top left side of the

o p e n circuit until the time period of 15 seconds for

junction box.

K 9 or 30 seconds for K6 has elapsed. At the end of

d. Installation. Installation shall be in the

t h e timing period there should be a reading of zero

reverse order of removal.

ohms across terminals 2 and 3.

c. Removal. Tag and disconnect the remaining

4-40. Time Delay Relays, K6 and K9

wire leads. Remove the two screws on the right

a. Function. The air conditioner is equipped

b a c k side of the junction box and the screw on the

with two time delay relays. Time delay relay K6

r i g h t end of the junction box to remove the bracket

p r e v e n t s the compressor from starting for a time of

to which the time delay relays are mounted.

30 seconds after selection of the cooling mode of

Remove the time delay relays from the bracket by

operation. Time delay relay K9 prevents the

removing the four nuts and screws which secure

condenser/evaporator

fan

motor

from

starting

t h e m to the top and bottom surfaces of the bracket.

high speed for 15 seconds after placing the air

T i m e delay relay K9 is mounted on the top surface

c o n d i t i o n e r in any of the four modes of operation.

and K6 on the bottom surface.

b. Testing. Remove the junction box from the

d. Installation. Installation shall be in the

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

reverse order of removal.

t h e leads to contacts 2 and 3. Using an ohmmeter,

m e a s u r e the resistance across contacts 2 and 3 with

4-41. Compressor and Heater Control Relay

the control circuit de-energized. Reading should

relay

a. Function. T h e

compressor

4-13