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FIGURE 18
FIELD WIRING HOT GAS REHEAT UNITS (Using
A Humidity Sensor With More than 150Ft. Wire
Runs)
ISOLATED 24V
TRANSFORMER
9
8
P298
J298A
1
2
B
3
4
C
5
6
7
D
10
A91
VIN
VO
GND
R
C
AI-1
HUM
TMP
DO-1
C
DI-1
DO-2
NOT
CONNECTED
NOT
CONNECTED
DRAIN
A55 UNIT
CONTROLLER
Blower Operation and Adjustments
Belt Drive With Supply Air Inverter or Direct Drive
Units -
The blower rotation will always be correct on units
equipped with an inverter or a direct drive blower.
Checking blower rotation is not a valid method of
determining voltage phasing for incoming power.
IMPORTANT
Three Phase Scroll Compressor Voltage Phasing
Three phase scroll compressors must be phased se
quentially to ensure correct compressor and blower*
rotation and operation. Compressor and blower are
wired in phase at the factory. Power wires are color-
coded as follows: line 1-red, line 2-yellow, line 3-blue.
1-Observe suction and discharge pressures and blow
er* rotation on unit start-up.
2-Suction pressure must drop, discharge pressure must
rise and blower* rotation must match rotation marking.
If pressure differential is not observed or blower* rota
tion is not correct:
3-Disconnect all remote electrical power supplies.
4-Reverse any two field-installed wires connected to
the line side of S48 disconnect or TB13 terminal strip.
Do not reverse wires at blower contactor.
5-Make sure the connections are tight.
Discharge and suction pressures should operate at
their normal start‐up ranges.
*Supply air inverter driven motors should rotate in the
correct direction; verify scroll compressor rotation
separately. Contact technical support if the blower is
rotating incorrectly.
Units Equipped With Belt Drive Blowers Controlled
by an Inverter OR Direct Drive Blowers Equipped
With Optional Voltage or Phase Detection -
The Unit
Controller checks the incoming power during start-up. If
the voltage or phase is incorrect, the Unit Controller will
display an alarm and the unit will not start.
A-Blower Operation
Note - On units with staged blowers, use the Unit
Controller to start the blower. Refer to the appropriate
start-up section.
WARNING
1-Make sure that unit is installed in accordance with the
installation instructions and applicable codes.
2-Inspect all electrical wiring, both field‐ and factory‐
installed, for loose connections. Tighten as required.
3-Check to ensure that refrigerant lines do not rub against
the cabinet or against other refrigerant lines.
4-Check voltage at disconnect switch. Voltage must be
within range listed on nameplate. If not, consult power
company and have voltage condition corrected before
starting unit.
5-Make sure filters are new and in place before start‐up.
Initiate blower only (G) demand at thermostat according
to instructions provided with thermostat. Unit will cycle on
thermostat demand. The following steps apply to
applications using a typical electro-mechanical
thermostat.
1- Blower operation is manually set at the thermostat
subbase fan switch. With fan switch in
ON
position,
blowers will operate continuously.
2- With fan switch in
AUTO
position, the blowers will
cycle with demand. Blowers and entire unit will be off
when system switch is in
OFF
position.
B-Blower Access
The blower assembly is secured to a sliding frame which
allows the blower motor assembly to be pulled out of the
unit. See figure 19, 20 or 21.
1-
Belt Drive Blowers -
Loosen the reusable wire tie
which secures the blower wiring to the blower motor
mounting plate.
Direct Drive Blowers -
Loosen the reusable wire tie
which secures the controls and high voltage blower
wiring to the blower housing.
2- Remove and retain screws on either side (and on the
front for direct drive) of sliding frame. Pull frame
toward outside of unit.
3- Slide frame back into original position when finished
servicing. Reattach the blower wiring in the previous
location using the wire tie.
4- Replace retained screws.
