Daikin Rebel Applied DPSA Installation And Start-Up Manual page 69

Scroll Compressor Rotational Direction
Scroll compressors only compress in one rotational direction.
Three-phase compressors can rotate in either direction
depending upon phasing of the power to L1, L2, and L3.
Since there is a 50/50 chance of connecting power to cause
rotation in the reverse direction. Use a phase rotation meter
to confirm phasing is clockwise. If the compressor is rotating
properly when energized, the suction pressure will decrease
and the discharge pressure will increase. If the compressor is
rotating in reverse, the sound level is louder and current draw
is reduced substantially. After several minutes of operation
rotating in the incorrect direction, the compressor's motor
protector may trip. Tripping will not damage the compressor as
long as it does not continue to repeat this cycle.
All three-phase compressors are wired the same internally.
Therefore, once the correct phasing is determined for a specific
system or installation, connecting properly phased power
leads to the same terminals should maintain proper rotational
direction.
Perform the following procedure on all units:
1. At the keypad, The cooling set point value in
Unit\Cooling Set-Up\Occ Clg Spt
below the Control Temp shown in the same menu. In
addition, on DAC units, adjust the value in
Unit\CoolingSet-Up\DAT Clg Spt
shown in Disch Air in the same menu
2. Place the unit into cooling mode through the keypad
Quick Menu\Ctrl Mode = Cool Only.
menu
3. Verify that the low ambient compressor lockout
temperature setpoint,
Cooling Setup\Clg Lo OAT Lk
outside air temperature (OA Temp) is shown in the same
menu.
NOTE: Do not attempt to operate the compressors if the
outdoor air is below 50°F. See the caution statement
under "Compressor Startup".
4. Note that if the unit has an economizer and the outdoor
air enthalpy is low, the economizer must fully open
before the controller will energize mechanical cooling.
5. When the outdoor air damper has fully opened and the
time delay has expired, the liquid line solenoid and the
compressor should start.
a. Verify that there is a call for cooling by checking
the keypad menu
should be in Cooling.
b. Check the keypad to ensure the compressors have
Main Menu\ViewStatus\Unit Status/
been enabled.
Settings\Clg Status =.
run if this reads (Enabled).
6. Verify that compressor #1 starts. If the compressor motor
hums but does not run, verify that it is getting three-
phase power.
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Commission
will need to be adjusted
Commission
below the temperature
Main Menu\Commission Unit\
is set below the current
Quick Menu\Unit State =
. This
The compressors will only
7. The compressor should operate continuously while there
is a call for cooling. If the compressor cycles on its low
pressure switch, due the following:
a. Verify that the circuit is not low on refrigerant.
b. Check for low supply airflow.
c. Check for clogged filters.
d. Check for restricted ductwork.
e. Check for very low temperature return air entering
the unit.
f. Verify that the liquid line components, expansion
valve, and distributor tubes are feeding the
evaporator coil.
g. Verify that all air handling section panels are
closed.
h. Verify that the liquid line solenoid valves are
completely open (energized).
8. If the refrigeration circuit has multiple compressors, verify
that the compressors stage properly. As the circuit load
increases the second compressor (if available) will be
energized.
9. Verify that the condenser fans are cycling (ON/OFF)
and rotating properly (blowing air upward). When a
compressor starts, at least one condenser fan should
also start. MT4 should control the remaining condenser
fans based on ambient air conditions. Refer to the unit
wiring diagrams for control wiring.
10. After 15 minutes of run time, check the oil level in the
compressor sightglass (if available). If low oil or heavy
foaming is observed, it is possible that liquid refrigerant
is returning to the compressor. Check the suction
superheat It should be between 10°F (-12°C) and 14°F
(-10°C).
11. Place the unit into the "Fan Only" mode through the
Main Menu\Quick Menu\Ctrl Mode = fan
keypad menu
only
.
12. Check refrigerant circuit #2 by repeating steps 2
through 9.
13. Check the compressor oil level again. If oil level is low,
consult Technical Support before adding oil.
14. Verify that the condenser refrigerant subcooling for each
refrigeration circuit at full capacity is between as shown
in Table 14
Table 14: Expected Subcooling for Compressor Startup
Outdoor Air Temp . (F)
75-80
81-90
91-95
95-105
69
Unit Operation
Subcooling (F)
7-10
10-12
12-15
15-20
IM 1287-4 • REBEL APPLIED ROOFTOP