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Outside Air Thermostat - TM-5-4120-337-140047
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TM-5-4120-337-14 Air Conditioner Vertical: Compact Self-Contained Air Cooled Electrical Motor Driven Manual
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Section XIII. MAINTENANCE OF T H E REFRIGERANT
resistance (should read-zero ohms) between the
banks of the heating elements are energized if the
associated normally closed contacts. The resistance
control thermostat is, set above evaporator return
between the normally open contacts should read
air  temperature.
infinity on the ohmmeter. Then apply minimum
b. Testing. Refer to figure 1-5 and, using an
rated test voltage to relay coil. Contacts must
ohmmeter, measure resistant; between terminals A
r e v e r s e from open to closed as noted by a clicking
and B. Meter should read approximately 10 ohms.
noise. Finally, measure the contact resistance with
Next, measure resistance between heater terminals
t h e relay energized, The ohmmeter readings should
and casing. Must read open circuit ohms.
b e infinite for the normally closed contacts and zero
c. Removal.
ohms for the normally open contacts. Check for
(1) Remove the top panel (para 4-11).
resistance from each of the terminals to the case of
( 2 ) Remove the nuts and washers securing the
the air conditioner. Open circuit resistance should
w i r i n g to the heating elements and tag and remove
the wiring.
be indicated.
c. Removal.
( 3 ) Loosen the retaining screw and remove the
clamp which secures the heater to the heater
(1) Remove the top panel (para 4-11).
support bar.
(2) Tag and disconnect the ten wire leads.
(4) Lift the heating element out of the air
(3) Remove the two nuts, washers and screws
conditioner.
and remove the relay.
d. Installation. Installation should be per-
d. Installation. Installation shall be in the
f o r m e d in reverse order of removal. Be sure that all
reverse order of removal.
wiring is reconnected properly and that all con-
4-53. Wiring Harnesses
nections are tight. Keep wiring terminals oriented
a. Function. There are six wiring harnesses
so that shorts do not occur across the heater ter-
included in the air conditioner which serve to
minals.
distribute the power and control wiring to the
Heater Thermostat
various electrical components included. In addition
to these harnesses there are thirty-nine individual
a. Function. The heater thermostat protects the
electrical leads which are not integral to the
air conditioner from overheating when in the
aforementioned  harnesses.  Two  harnesses  and
heating mode. It cuts off the power supply to all
twenty-seven electrical leads are included in the
heating elements upon a rise to a temperature of
90 5 C. This situation should normally only
junction box assembly. One harness and three
electrical leads are included in the control panel
o c c u r in the absence of air flow across the heating
assembly. Three harnesses and nine electrical leads
elements.
are included in the air conditioner outside the
b. Testing. Using  an  ohmmeter  check  for
control panel and junction box.
continuity between the three terminals of the
b. Inspection and Test. Inspection and test of
thermostat. There should be zero resistance across
the wiring harnesses consists of visually checking
each pair of terminals. Check for resistance from
f o r broken or cracked insulation, poor solder joints
each of the terminals to the case of the air con-
or loose terminal connections. Proper operation of
ditioner. Open circuit resistance should be in-
t h e air conditioner in all modes of operation is the
dicated.
c. Removal.
b e s t check of the various wiring harnesses. Refer to
F i g u r e Numbers 1-5 and 1-7 in the event there is a
(1) Remove the top panel (para 4-11).
malfunction in the operation of the air conditioner
( 2 ) Tag and remove the three wire leads from
for electrical check points. Use a multimeter to
the heater thermostat.
check for continuity from point to point and to
(3) Remove the two screws, nuts and washers
which secure the heater thermostat to the heater
check for shorts between connections.
c. Removal.
support bar and remove the thermostat.
d. Installation. Installation shall be in the
(1) P o w e r d i s t r i b u t i o n w i r i n g h a r n e s s .
reverse order of removal.
(a) Remove the junction box (para 4-36).
(b) Remove the top panel (para 4-11).
4-52. Fan Speed Relay
(c) Remove the four slip-on connectors
a . Function. This relay is used to control the fan
from capacitors C1 and C2. Tag the wires before
speed as selected by the fan speed switch on the
disconnecting.
control panel or the fan speed control pressure
(d) Disconnect P7 from connector J7 on the
s w i t c h which closes upon an increase in refrigerant
top portion of the evaporator/ condenser partition,
pressure. This relay is a four pole double throw type
P3 from connector J3 on the compressor and P10
w i t h four normally open contacts and four normally
from J10 on the junction box.
closed contacts.
(e) R e m o v e t h e t w o s c r e w s , s p a c e r s a n d
b. Testing. U s e a n  o h m m e t e r a n d m e a s u r e

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