MCi Crusader II 1989 Maintenance Manual page 488

Date
1-1-89
Page
16-18
MC-9 MAINTENANCE MANUAL·
9. Subtract the average equivalent temperature (from
step 6) from the average remote bulb temperature (from
step 7). Example:
Avg Temp. at Bulb: 49°F (10°C)
SubtractAvgEquiv.Temp.atFitting: -41°F ( 5.25°C)
Difference: 8°F ( 4.75°C)
The difference in the average temperatures should be
from 10-12°F (5-6°C). lfmorethan 12°F (6°C) or less than
10°F (5°C), as in the example, the expansion valve
requires adjustment (see step 10) and the entire proce-
dure should be repeated.
CAUTION: Before adjusting the expan-
sion valve, check for a restricted suction
llne, plugged fllter dryer or for a partially
opened valve.
To verify the need for expansion valve adjustment perform
steps 10-17.
10. Remove the gauges from the expansion valve and
install them at the compressor gauge connections; pres-
sure gauge in suction lineandtemperaturegaugeinstalled
to indicate suction line temperature.
11. Run the system for 10 minutes, set at 82°F (28°C).
12. Measure and record the line pressure and temperture.
13. Determine equivalent temperature from the chart.
Example: 30 psi (206 kPa) equals 32°F (0°C).
14. Subtract the equivalent temperature from the line
temperature indicated on the tern perature gauge. Example:
Temperature Gauge Reading: 40°F (4°C)
Subtract Equivalent Temperature: -32°F (0°C)
Answer: 8°F (4°C)
15. The answer represents the indicated superheat. If
this temperature is approximately equal to the superheat
temperature determined in step 8, above, there is no appar-
ent restriction in the suction line or filter dryer, nor an open
valve. Proceed to step 17.
16. If the answer (step 14) is not approximately equal to
the superheat temperature determined in step 8, determine
the cause of the different readings (e.g. suction line restric-
tion, clogged futer dryer or malfunctioning valve) and
repair the defective part. Repeat steps 1-16 to determine
need for expansion valve adjustment.
17. To adjust the superheat setting on the expansion
valve, turn the adjustment screw clockwise to increase
superheat temperature, counterclockwise to lower super-
heat temperature.
18. Repeat steps 2 thru 9 to verify correct valve setting.
MAINTENANCE-
1. Pump down the system as directed earlier in this
section.
2. See figures 16-19 and 16-20. At ttie expansion valve,
disconnect the external equalizer line from the underside of
the power head and unclamp the remote control bulb from
the evaporator coil outlet line.
PRESSURES AND EQUIVALENT TEMPERATURES (FREON 12)
STANDARD UNITS
METRIC UNITS STANDARD UNITS METRIC UNITS
PSI
OF
KPA
oc
PSI
OF
KPA
oc
25 28
171
-2
48 51 329 11
26 29
178 -2
49
52 336
11
27 30 185
-1 50 53 343 12
28
31
192 -1 51 54 349 12
29 32
199 0 52 55 356 12
30
33
206
1
53 56 363 13
31
34 212
1 54 57 370 13
32
35 219 2
55 58 377 14
33
36 226
2 56 59 384 14
34 37
233 3
57
60 390 15
35 38
240
3 58 60 397 16
36 39
247
4
59 61 404 16
37 40
253
4
60 62 411 16
38
41 266 5
61 63 418 17
39
42
267 6 62 64 425 17
40 43
275 6
63 64 432
18
41
44 281
7 64
65
438
18
42
45 288
7 65 66 445 18
43
46 295
8 66
67
452 19
44
47 301 8
67 68
459 19
45 48
308 9
68 68
466 20
46
.
49 315 9
69 69 473 21
47 50 322
10 70 70 480 21