16
START-UP, 2-SPEED INDOOR
FAN MOTOR OPTION
Compressor Rotation
Units equipped with a VFD on the indoor fan motor cannot use ro-
tation direction of the indoor fan motor and fan to visually confirm
a correct phase connection to the unit and compressors. Correct
phases to equipment for proper compressor rotation. The VFD
will maintain the same rotation as input phases are changed. Pres-
sure gauges MUST BE USED during cooling system start-up to
confirm correct compressor rotation and operation.
Indoor Fan Motor
Raise the cooling set point at the space thermostat to higher than
space temperature. Switch the thermostat’s FAN switch to CONT
(Continuous) position. Fan motor will start, run at reduced speed.
Check for fan rotation direction. To reverse the fan rotation, dis-
connect all power to unit and then switch two motor power leads
between the VFD and the motor. Restore unit power and recheck
fan rotation direction.
Check fan motor speed. Motor shaft should be rotating at 1150 to
1180 rpm (19.2 to 19.7 r/s).
Switch the thermostat’s FAN switch to AUTO position. Fan motor
will stop.
Cooling with 2-Speed Indoor Fan Motor
FIRST STAGE (Y1)
Set the thermostat FAN switch to AUTO and the SYSTEM switch
to COOL. Slowly lower the cooling set point until first stage com-
pressor starts. Indoor fan motor also starts, runs at reduced speed.
SECOND STAGE (Y2)
Lower the cooling set point until second stage compressor starts.
Indoor fan motor will switch to high speed.
Check fan motor speed. Motor shaft should be rotating at 1725 to
1760 rpm (28.8 to 29.3 r/s).
Confirm compressors are running at correct rotation by checking
suction and discharge pressures. To reverse the compressor rota-
tion, disconnect unit power and switch two of the unit’s main pow-
er leads. Restore unit power and recheck compressor operation.
Reset thermostat cooling set point to a position above space tem-
perature. Both compressors will shut off. Indoor fan motor will
stop immediately.
524J, 548J/549J/551J/558J SERIES UNITS
Indoor fan motor will stop immediately.
580J/581J SERIES UNITS
Indoor fan operation will continue for 45-seconds, then stop.
Operating Sequences, 2-Speed Indoor Fan Motor
Option
VENTILATION (FAN ONLY)
Ventilation mode occurs when the indoor fan runs without accom-
panying cooling or heating system operation. The thermostat’s
FAN selection switch will be in CONT (Continuous) position; no
demand for cooling or heating will be present.
580J/581J SERIES UNITS
The thermostat’s G terminal is energized with 24-v. This signal is
conveyed to the 48 Series unit’s Central Terminal Board (CTB) at
the field connection TSTAT terminal strip at terminal G. The 24-v
signal follows an internal trace path through jumper JMP6 to con-
nector CONTL BOARD pin 1. A harness wire connects pin 1 to
IGC board terminal G. The IGC energizes its fan relay, energizing
IGC terminal IFO. This 24-v signal follows a harness conductor
back to the CTB’s CONTL BOARD connector at pin 6 and pin 7.
Pin 7 is connected to the Fan Speed Board at connector J1 pin 4.
Relay K3 is energized. A 24-VDC signal is passed to the VFD
terminal 14. The VFD starts the indoor fan motor and runs it at
40 Hz for reduced/low speed operation.
551J, 580J/558J SERIES UNITS
The thermostat’s G terminal is energized with 24-v. This signal is
conveyed to the 551J,580J/558J Series unit’s Central Terminal
Board (CTB) at the field connection TSTAT terminal strip at ter-
minal G. The 24-v signal follows an internal trace path through
jumper JMP6 to connector CONTL BOARD pin 1. A harness
wire connects pin 1 to the Fan Speed Board at connector J1 pin 4.
Relay K3 is energized. A 24-VDC signal is passed to the VFD ter-
minal 14. The VFD starts the indoor fan motor and runs it at 40 Hz
for reduced/low speed operation.
549J, 548J SERIES
The thermostat’s G terminal is energized with 24-v. This signal is
conveyed to the 549J/548J Series unit’s Central Terminal Board
(CTB) at the field connection TSTAT terminal strip at terminal G.
The 24-v signal follows an internal trace path to connector RE-
HEAT/DEFROST pin 1. A harness wire connects pin 1 to DFB
board terminal P2-3. The DFB energizes its fan relay, energizing
DFB terminal P3-8. This 24-v signal follows a harness conductor
back to the CTB’s REHEAT/DEFROST pin 2. An internal trace
path connects pin 2 to CONTL BOARD connector at pin 1. Pin 1
is connected to the Fan Speed Board at connector J1 pin 4.
Relay K3 is energized. A 24-VDC signal is passed to the VFD
terminal 14. The VFD starts the indoor fan motor and runs it at
40 Hz for reduced/low speed operation.
Cooling (FAN Switch in AUTO)
FIRST STAGE (Y1)
When the thermostat initiates a call for First Stage Cooling by
closing its Y1 contacts, the thermostat also energizes its G termi-
nal. Follow the sequence under Ventilation above. Fan Speed Re-
lay board relay K3 is energized, causing the VFD to start the in-
door fan motor and run at 40 Hz for reduced fan speed operation.
When space temperature drops to satisfy the thermostat Y1
demand, contact Y1 opens de-energizing terminal G. Relay K3 is
de-energized. The relay board output at J2-2 to the VFD is re-
moved and indoor fan motor ramps down to stop.
SECOND STAGE (Y2)
If space temperature continues to rise, thermostat Y2 demand will
be initiated. Contact Y2 will close, sending a 24-v signal to CTB’s
TSTAT terminal strip at Y2. An internal path passes this signal to
connector DDC/TSTAT pin 6. A harness wire carries this signal to
Fan Speed Relay board pin J1-3. Relay K2 is energized. The relay
board’s output to VFD at pin J2-2 is de-energized and the output at
J2-3 is energized, causing the VFD to shift its output to the indoor
fan motor to 60 Hz. The indoor fan motor ramps up to full/high
speed operation.
When the space temperature drops to satisfy thermostat Y2 de-
mand, contact Y2 opens de-energizing terminal Y2. Relay K2 is
de-energized, removing the VFD input at terminal 15. Fan Speed
Board output at pin J2-2 is restored to the VFD at terminal 14;
VFD shifts back to 40 Hz output to the indoor fan motor and mo-
tor shifts back to reduced speed operation.
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