4-12
T-312
b. Use a digital volt-ohmmeter to measure voltage
across the transducer and compare to values in
Table 4-5. A reading within two percent of the values
in the table would be considered good.
Table 4-5. Suction and Discharge Pressure
Transducer (SPT and DPT) Voltage
Psig Voltage Psig Voltage Psig Voltage
20”
0.369
105
1.495
220
2.622
10”
0.417
110
1.544
225
2.671
0
0.466
115
1.593
230
2.720
5
0.515
120
1.642
235
2.769
10
0.564
125
1.691
240
2.818
15
0.614
130
1.740
245
2.867
20
0.663
135
1.789
250
2.916
25
0.712
140
1.838
255
2.965
30
0.761
145
1.887
260
3.014
35
0.810
150
1.936
265
3.063
40
0.858
155
1.985
270
3.112
45
0.907
160
2.034
275
3.161
50
0.956
165
2.083
280
3.210
55
1.007
170
2.132
285
3.259
60
1.054
175
2.181
290
3.308
65
1.103
180
2.230
295
3.357
70
1.152
185
2.279
300
3.406
75
1.204
190
2.328
305
3.455
80
1.250
195
2.377
310
3.504
85
1.299
200
2.426
315
3.553
90
1.348
205
2.475
320
3.602
95
1.397
210
2.524
325
3.651
100
1.446
215
2.573
330
3.700
4.16 REPLACING SENSORS AND
TRANSDUCERS
a. Turn main battery disconnect switch to OFF position
and lock.
b. Tag and disconnect wiring from defective sensor or
transducer.
c. Remove and replace defective sensor or transducer.
d. Connect wiring to replacement sensor or transducer.
e. Checkout replacement sensor or transducer. (Refer
to paragraph 4.13, 4.15 or 4.14, as applicable.)
4.17 SERVICING MAIN EVAPORATOR BLOWER
ASSEMBLY
a. Turn main battery disconnect switch to OFF position
and lock.
b. Remove access door located in the #3 baggage
compartment. To remove the access door, unlatch,
then open the door enough to slide the hinge pins out
of the pin brackets.
c. Disconnect electrical connections to the motor.
d. Remove blower transitions ducts.
e. Remove the four bolts securing the evaporator motor
mounting plate, motor and blower housing assembly
to the bottom panel.
f. Remove motor and blower wheel assembly by sliding
out of evaporator housing.
g. Repair or replace any defective component(s), as
required.
h. Replace by reversing steps b. thru f.
4.18 ACCESSING MAIN EVAPORATOR MOTOR
BRUSHES
a. Turn main battery disconnect switch to OFF position
and lock.
b. Remove access door. (Refer to 4.17.b.)
c. Disconnect electrical connections to the motor.
d. With a marker, trace the outline of the motor on the
motor plate.
e. Remove the four brush access doors on the motor.
f. Service two brushes (top front and top rear).
g. Remove the four bolts securing the evaporator motor
to the mounting plate.
h. Rotate the motor to gain access to the lower front
brush.
i. Rotate the motor the opposite way to gain access to
the lower rear brush.
j. Rotate the motor back to its feet and position back to
its original position guided by the outline drawn in step
d.
k. Re--secure the motor with the four bolts removed in
step g. Check fan rotation, insuring that the fan
wheels do not make contact with the fan housings.
l. Complete the procedure by performing steps a. thru
c. in reverse.
4.19 SERVICING MOTOR BRUSHES
If the brushes are broken, cracked, severely chipped, or
worn to 1/3 their original length, replace them.
a. Remove the four brush access doors on the motor.
b. With fingers or a suitable hook, lift the brush spring
end up so the brush may slide up and out of the
holder. Loosen the brush screw to remove the brush
shunt terminal. Remove the brush.
c. To replace, lift the brush spring and place the brush in
the holder. Position the end of the spring on top of the
brush.
d. Connect the brush shunt terminal to its proper
crossover with the brush screw assembled loosely.
NOTE
Assure positioning of the brush to permit the
brush shunt to travel freely in the holder slot
as the brush wears. If the brush hangs up,
commutator damage and motor failure will
result
e. Tighten screw.
