536636-UIM-A-1209
10
Johnson Controls Unitary Products
CONTROL WIRING USING COMMUNICATING
CONTROLS
Use the wiring diagram below to connect the air handler control, Com-
municating Control (wall thermostat) and communicating outdoor unit.
Be sure that all of the “A” terminals are connected together, all of the “B”
terminals are connected together, all of the “GND” or “C” terminals are
connected together and all of the “R” terminals are connected together.
See Figure 13. When using a fully communicating system, the large
screw terminals (C, G, R, etc.) on the air handler control are not used.
The four small screw terminals in the terminal block on the end of the air
handler control should be used.
HUMIDITY SWITCH INPUT
The air handler control is designed to work with a humidity control that
closes when the humidity is below the set-point. The control is open
when the humidity is above the set-point. This humidity control may be
referred to as a humidistat or a dehumidistat.
The humidity switch controls both humidification and de-humidification
operation of the control. The control provides humidification using the
HUM OUT relay output and de-humidification by lowering the blower
speed. This is accomplished using the de-humidification input of the
motor for variable speed models. The humidity switch should be con-
nected to the R and HUM terminals of the control. See Figures 11 and
12.
The 24 volt power supply is provided by an internally wired low voltage
transformer which is standard on all models, However, if the unit is con-
nected to a 208 volt power supply, the low voltage transformer must be
rewired to the 208 volt tap. See the unit wiring label.
Field supplied low voltage wiring can exit the unit on the top right hand
corner or the right hand side panel. Refer to Figure 3.
Remove desired knockout and pierce foil faced insulation to allow wir-
ing to pass through. Use as small of a hole as possible to minimize air
leakage.
Install a 7/8” plastic bushing in the selected hole and keep low voltage
wiring as short as possible inside the control box.
To further minimize air leakage, seal the wiring entry point at the outside
of the unit.
The field wiring is to be connected at the screw terminals of the control
board. Refer to Figures 11 or 12.
The low voltage connections may be connected to the screw terminals
or the quick connect terminals. The screw terminals and the quick con-
nect terminals are physically connected on the control board.
SECTION VI: REQUIRED CONTROL
SET-UP
IMPORTANT:
The following steps must be taken at the time of installa-
tion to insure proper system operation.
1.
Consult system wiring diagram to determine proper thermostat
wiring for your system.
2.
If heat kit is installed, change HEAT/NO HEAT jumper from NO
HEAT to HEAT position.
3.
If a humidistat is installed, change HUM STAT jumper from NO to
YES.
4.
Set the MODE jumper to A/C (Air Conditioner) or HP (Heat Pump)
position depending on the outdoor unit included with the system.
5.
Set airflow and comfort setting jumper to proper positions.
FIGURE 13:
Air Handler with Communicating AC or HP
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All wiring must comply with local and national electrical code
requirements. Read and heed all unit caution labels.
It is possible to vary the amount of electric heat turned on during the
defrost cycle of a heat pump. Standard wiring will only bring on the
first stage of electric heat during defrost. See Heat Output and Limit
Connections and Table 5 for additional information on heat during
defrost cycle.
TABLE 3:
Low Voltage Connections
Terminal Signal
Comment
R
24 VAC power (fused)
G
Continuous Fan operation
Y/Y2
Second or full stage
compressor operation
Y1
First stage compressor
operation
Not used with outdoor units
having one stage compressors.
W2
Second stage heat operation
W1
First stage heat operation
O
Reversing valve operation
24 VAC will be present at this
terminal when the MODE
jumper is in the AC position.
This is normal.
HUM
Humidity switch input
24 VAC will be present at this
terminal when the HUM STAT
jumper is in the NO position.
This is normal.
X/L
Connection point for
heat pump fault indicator
This terminal is a connection
point only and does not affect
air handler control operation.
COM
24 VAC common
NOTICE
NOTICE
