Thermo King Super II SR+, Manual, Page: 84 / 145

Refrigeration Maintenance (Rev 6/98)
74
NOTE: If the ball and liquid level in the receiver sight
glass drops during step 4, the unit is not overcharged
and it is not necessary to complete the procedure.
5. Remove the condenser cover to rapidly reduce dis-
charge pressure.
6. Observe the receiver tank sight glass and the unit dis-
charge pressure.
7. By the time the discharge pressure drops approximately
345 kPa (50 psi), the ball in the receiver tank sight glass
should begin to move and the liquid level should drop.
a. When the discharge pressure stabilizes, the ball
and liquid level will rise.
b. If the ball will not begin to move or the liquid level
will not drop, the unit most likely has an over-
charge of refrigerant. The refrigerant level should
be adjusted.
To adjust the refrigerant level:
1. With the unit operating in high speed cool, use a gauge
manifold set to pump refrigerant from the RECEIVER
TANK into an approved container.
2. When the liquid level begins to drop in the receiver
tank sight glass, close the hand valve on the gauge
manifold immediately. Allow new level to stabilize (1
to 2 minutes).
3. If the liquid level is less than a full sight glass, adjust by
adding vapor through the suction service valve. With
the unit running in high speed cool, add vapor until the
ball is near the top of the sight glass. Allow to stabilize
(1 to 2 minutes).
NOTE: When adding refrigerant, maintain a dis-
charge pressure of at least 1896 kPa (275 psi).
4. Repeat overcharge test.
Moisture Indicating Sight Glass
The receiver tank is equipped with a moisture indicating
sight glass. The outer edge of each sight glass has a colored
ring approximately 2.5 mm (0.1 in.) thick. The color of the
ring indicates the moisture content of the refrigerant, but it
is not completely reliable.
Green = Dry
Chartreuse = Caution
Yellow = Wet
Moisture Indicating Sight Glass
A system has to run for at least 15 minutes to change the
color of the indicator ring after the moisture content of the
system has been changed. For example, evacuating a system
to remove the moisture will not change the color of the indi-
cator ring until the system has been recharged and then
operated for at least 15 minutes.
REFRIGERANT LEAKS
Use a reliable leak detector (e.g., electronic detector or
Halide torch) to leak test the refrigeration system. Inspect
for signs of oil leakage which is the first sign of a leak in the
refrigeration system.
1 Colored Ring
2 Floating Ball
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