MCi Crusader II 1989 Maintenance Manual page 487

Date
1-1-89 Page
16-17
MC-9 MAINTENANCE MANUAL
G
EVAPORATOR
..I ~
...,,,,,,,-
-~~
,~,
~
'
J.\
SUPERHEA
\, .· ""'- CHECK Fl
Figure 16-20: Superheat Check Attings
for Pressure Gauge Connection
Standard Units
36
psi=
39°F
37 psi= 40°F
41 psi= 44°F
39 psi= 42°F
Metric Units
247
kPa
=
4°C
253 kPa = 4°C
281 kPa
=
7°C
267 kPa = 6°C
6. Determine the average equivalent check fitting temper-
ature by adding the four temperatures and dividing the sum
by four. Example:
39°F
+40
+44
+42
TOTAL: 165°F
165+4 = 41 °F Average
4°c
+4°C
+6°C
+7°C
21°C
21 +4 = 5.25°C Average
HIGH READING 54°F
(13°c>
LOW READING 44°F
(7°C)
EX.uFLE OF REAOM3S TAKEN:
AIC PRESSURE GAUGE CONVERTED
TO
TEMPERATURE AT EXPANSION
VALVE FlTTING :
TEMPERATURE AT
REMOTE BULB
37 PSh 40-F (253 KPAa 4•C)
i
• FROM PRESSURE/
TE ....
CHART,
BELOW
LOW READING
HIGH READING
44°F (7°C)
TO AND SUPERHEAT TEMP :
4 9"f' • 4o-F • 9"F
(10"C • 4°C•e<'Cl
SUPER HEAT TEMP.a 9"F (e"Cl
AVERAGE
OF
LOW AND HIGH
READINGS IS 49 F (10 Cl
Figure 16-21: Temperature Gauge Rea!,iings
7. Determine the average remote bulb temperature from
the high and low
temperature
readings recorded (bin step
4). Example:
High Reading: 54°F (12°C)
Plus Low Reading: +44 ( 8°C)
Total: 98°F {20°C)
Divide by 2: 98.;. 2
=
49°F (20 .;. 2
=
10°C Average)
8. Subtract the lowest equivalent temperature recorded
at the check fitting from the lowest temperature from the
temperature gauge. The answer (difference) is the super-
heat temperature. Example:
Lowest Remote Bulb Temperature: 44°F (8°C)
Subtract Lowest Equivalent Temperature: -39°F {4°C)
Superheat Temperature: 5°F (4°C)
The superheat temperature should be a minimum of
4°F
(2°C). If less than 4°F (2°C), the expansion valve should be
adjusted (see step 10) and the entire procedure repeated.
NOTE:
If
the expansion valve needs
adjustment at this point, proceed to step
10.
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