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l;rusaaer
MC-8
[ e.c,
16-33
ELECTRICAL CONTROLS
BLOWER CUT-IN RELAY
This relay is located in the rear junction panel in
the L.H. side of the engine compartment.
When the alternator is in operation, the relay cuts
in, supplying current to the A/C and Heating control
switch on the driver's panel. Activation of this switch
supplies current to the magnetic switches for the
evaporator and condensor motors.
LINES
&
FITTINGS
All
lines
are
copper
tubing
or
Aeroquip
No. 1540 hose. The copper lines have soldered joints
and the large hose connections have a rubber "O"
ring seal.
LEAK TESTING
The most common method used is a Halide torch
consisting of an acetylene tank. a burner and a suc-
tion test hose.
CAUTION: Do not inhale fumes from leak detec~
tor.
The flow of acetylene to the burner causes a suc-
tion in the test line. Any refrigerant gas present will
be drawn through the hose and into the burner where
it decomposes into free acids.
These acids come in contact with the hot copper
reaction plate in the burner, causing color reaction in
the flame. A small concentration is indicated by a
green tint and a large concentration by an intense
blue.
Do not confuse this change in color with the
change caused by shutting off the air supply through
the hose by holding the end too close to an object.
The procedure for testing is:
1) Adjust flame so the top of the cone is ap-
proximately level or within one-half inch above
the plate.
2) Probe end of suction test tube around all joints,
valves, etc. When a leak has been found at a
soldered joint, that section of the system must be
pumped down. DO NOT solder if pressure exists
m the joint as pressure will force hot solder out.
If the system is empty, it is more economical to
put in just enough Freon to produce about 15 psi.
The pressure can then be raised to about 150 psi.
with dry nitrogen.
Note: This gas is put into the suction and
discharge shut-off valves at the compressor. The
receiver valves must also be opened. If no leaks are
found, dump this mixture, evacuate the system and
charge with refrigerant.
MAINTENANCE
""' Oecembe,, 1973
]
MANUAL
TEMPERATURE PRESSURES
The following
refrigerant
temperature-pressure
chart is used for adjusting the superheat and checking
for air in the system for refrigerant 12 and 500.
-20
-18
- I 6
- I 4
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
45
50
55
60
65
70
75
80
85
90
95
100
105
I I 0
115
120
125
130
135
140
145
150
155
160
PRESSURE
FREON 12
FREON 500
0.6
I
2
3
4
5
5
6
7
8
9
10
1 I
12
I 3
14
16
17
18
20
21
23
24
25
27
29
30
32
34
35
37
42
47
52
58
64
70
77
84
92
100
108
11 7
127
137
147
158
170
182
194
207
221
235
250
265
3
4
5
6
7
8
9
10
1 I
12
13
14
15
I 7
18
20
21
23
24
26
27
29
31
33
34
36
38
40
42
44
46
52
58
64
71
78
86
94
103
112
121
13 I
142
153
165
177
190
203
218
233
249
265
282
300
319
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