Daikin RoofPak RPS Series Installation And Maintenance Manual page 99

Scroll Compressor Rotational Direction
Venting refrigerant to atmosphere is not allowed per most
local laws and/or codes.
Scroll compressors only compress in one rotational direction.
Three-phase compressors 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, verify that the compressor rotates in the
proper direction after the system is installed. If the compressor
is rotating properly, suction pressure drops and discharge
pressure rises when the compressor is energized. If the
compressor is rotating in reverse, the sound level is louder and
current draw is reduced substantially. After several minutes of
operation, the compressor's internal protector trips.
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 rotation direction.
Perform the following procedure on all units:
1. At the keypad, set the cooling setpoint low enough
so that the controller will call for cooling. The value in
Temperature \ Zone Cooling \ Occ Clg Spt= will need to be
adjusted below the temperature shown in Temperature \
Zone Cooling \ Control Temp=. In addition, on DAC units,
the value in Temperature \ Discharge Cooling \ DAT Clg Spt=
will need to be adjusted below the temperature shown in
Temperature \ Discharge Cooling \ Disch Air=.
2. Place the unit into cooling mode through the keypad
menu System Summary \ System \ Ctrl Mode= Cool Only.
3. Verify that the low ambient compressor lockout
temperature setpoint, Temperature \ OA Damper \ OATComp
Lock= is set below the current outside air temperature
(shown in System Summary \ Temperatures \ OA Temp=).
NOTE: Do not attempt to operate the compressors if the
outdoor air is too cool. See the warning statement
under Compressor Startup on page
4. Close the S1 switch. Now refrigeration circuit #1 is
enabled, circuit #2 is disabled, and the MT III board
starts its 5-minute timing cycle. 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.
www.DaikinApplied.com
CAUTION
98.
Check, Test, and Start Procedures
5. When the outdoor air damper has fully opened and the
time delay has expired, liquid line solenoid valve SV1
should open and compressor #1 should start. If this does
not happen, perform the following:
a. Verify that there is a call for cooling by checking
the keypad menu System Summary \ System \
UnitStatus=. This should be in "Cooling."
b. Check the keypad menu System Summary \ System
\ Clg Status=. The compressors will only run if this
reads either "All Clg" or "Mech Clg."
c. Trace the control circuits.
6. Verify that compressor #1 starts. The compressor should
start when the solenoid valve opens. If the compressor
motor hums but does not run, verify that it is getting
three-phase power.
7. The compressor should operate continuously while there
is a call for cooling. If the compressor cycles on its low
pressure switch, perform the following:
a. Verify that the circuit is not short of refrigerant.
b. Check for low 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 service valves are
completely open.
8. Verify that the compressors stage properly. As the circuit
loads up, the second compressor (if available) will be
energized. For more information on staging sequences,
see IM 919, "MicroTech III Applied Rooftop Unit
Controller."
9. Verify that the condenser fans are cycling and rotating
properly (blowing air upward). When the compressor
starts, at least one condenser fan should also start.
The CCB1 should control the remaining condenser fans
based on outdoor air conditions. Look at keypad menu
Setup/ Service \ Compressor Setup \ Cond Fan1= (also look
at Cond Fan2=, Cond Fan3=, Cond Fan4=). The
page 47 shows recommended setpoints based on the
unit size. Cond Fan1 controls BO5, Cond Fan2 controls
BO6, Cond Fan3 controls BO7, Cond Fan4 controls
BO8. Refer to the unit wiring diagrams and
Fan Arrangement on page
99 IM 926-3 • ROOFPAK APPLIED SYSTEMS
Table 18 on
Condenser
6.