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WARNING
Rotating Components!
During installation, testing, servicing and troubleshoot-
ing of this product it may be necessary to measure the
speed of rotating components. Have a qualified or li-
censed service individual who has been properly
trained in handling exposed rotating components, per-
form these tasks. Failure to follow all safety precau-
tions when exposed to rotating components could re-
sult in death or serious injury.
12. Turn the 115 volt control circuit switch 1S1 "On".
13. Press the TEST START key to start the test. Remember
that the delay designated in step 11 must elapse before
the system will begin to operate.
14. Once each compressor or compressor pair has started,
verify that the rotation is correct. If a scroll compressor is
rotating backwards, it will not pump and a loud rattling
sound can be observed. Check the electrical phasing at
the load side of the compressor contactor.
If the phasing is correct, before condemning the com-
pressor, interchange any two leads to check the internal
motor phasing. Refer to the illustration in Figure 17 for
the compressor terminal identification. If the compressor
runs backward for an extended period (15 to 30 min-
utes), the motor windings can over heat and cause the
motor winding thermostats to open. This will cause a
"compressor trip" diagnostic and stop the compressor.
15. Verify that the oil level in each compressor is correct.
The oil level may be down to the bottom of the sightglass
but should never be above the sightglass.
16. Press the STOP key at the Human Interface Module in
the unit control panel to stop the compressor operation.
17. Repeat steps 8 through 16 for each compressor stage
and the appropriate condenser fans.
Verifying Proper Refrigerant Charge
1. Attach a set of service gauges onto the suction line and
liquid line gauge ports for each circuit. Refer to Figure 16
for the various compressor locations.
2. Open the Human Interface access door, located in the
unit control panel, and press the SERVICE MODE key to
display the first service screen. Refer to the latest edition
of the Trouble Shooting Guide for the SERVICE TEST
screens and programming instructions.
3. Program the following system components for the num-
ber 1 refrigeration circuit by scrolling through the dis-
plays;
Chilled Solution Pump (On)
All Compressors for each circuit (On)
Condenser Fans for each circuit (On)
Hot Gas Bypass (Disabled, if applicable)
Low Ambient Dampers (100%, if applicable)
4. Once the configuration for the components is complete,
press the NEXT key until the LCD displays the "Start test
in __Sec." screen. Press the + key to designate the de-
lay before the test is to start. This service test will begin
after the TEST START key is pressed and the delay des-
System Start-Up
ignated in this step has elapsed. Press the ENTER key
to confirm this choice.
WARNING
Rotating Components!
During installation, testing, servicing and troubleshoot-
ing of this product it may be necessary to measure the
speed of rotating components. Have a qualified or li-
censed service individual who has been properly
trained in handling exposed rotating components, per-
form these tasks. Failure to follow all safety precau-
tions when exposed to rotating components could re-
sult in death or serious injury.
5. Press the TEST START key to start the test. Remember
that the delay designated in step 4 must elapse before
the system will begin to operate.
6. After all of the compressors and condenser fans for the
number 1 circuit have been operating for approximately
30 minutes, observe the operating refrigerant pressures
and measure the system superheat and subcooling.
The outdoor ambient temperature must be between 65
and 105
o
F. When the temperatures are outside of these
ranges, refer to Table 10 for the recommended refriger-
ant capacities.
Note: Do Not release refrigerant to the atmo-
sphere! If adding or removing refrigerant is re-
quired, the service technician must comply with all
Federal, State and local laws. Refer to general ser-
vice bulletin MSCU-SB-1 (latest edition).
Subcooling
With the unit operating at "Full Circuit Capacity", acceptable
subcooling ranges between 14
Measuring Subcooling
a. At the liquid line service valve, measure the liquid
line pressure. Using a Refrigerant 22 pressure /
temperature chart, convert the pressure reading into
the corresponding saturated temperature.
b. Measure the actual liquid line temperature as close
to the liquid line service valve as possible. To ensure
an accurate reading, clean the line thoroughly where
the temperature sensor will be attached. After
securing the sensor to the line, insulate the sensor
and line to isolate it from the ambient air.
Note: Glass thermometers do not have sufficient
contact area to give an accurate reading.
c. Determine the system subcooling by subtracting the
actual liquid line temperature (measured in b) from
the saturated liquid temperature (converted in a).
Superheat
The reliability and performance of the refrigeration system
is heavily dependent upon proper expansion valve adjust-
ment. Therefore, the importance of maintaining the proper
superheat cannot be over emphasized. Accurate measure-
ments of superheat will provide the following information.
a. How well the expansion valve is controlling the
refrigerant flow.
51
o
F to 22
o
F.
o
F
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