User's Manual

536636-UIM-D-1211
8 Johnson Controls Unitary Products
CONVENTIONAL LOW VOLTAGE CONTROL WIRING
(24 VAC)
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 Figure 11 and 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.
* Optional dehumidification humidistat switch contacts open on humidity rise.
NOTES:
1. “Y/Y2” Terminal on air handler control board must be connected for full CFM and applications requiring 60 second blower off delay for SEER enhancement.
2. Remove humidistat jumper on air handler control board.
3. For heat pump applications - set MODE jumper on air handler control board to the HP position.
4. To change quantity of heat during HP defrost cycle - reverse connections at W1 and W2 on air handler control board.
.All wiring must comply with local and national electrical code require-
ments. 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.
NOTICE
NOTICE
TABLE 2: 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
FIGURE 12: Cooling Models with and without Electric Heat Wiring
Air Handler Control Wiring
Typical A/C - Cooling only Applications
THERMOSTAT
AIR HANDLER
BOARD
1-STAGE
AIR CONDITIONING
RR
G
Y
W1
W2
C
G
W1
W2
Y
C
Y/Y2
Y1
O
HUM
X/L
COM
HUMIDISTAT
*
THERMOSTAT
AIR HANDLER
BOARD
1-STAGE
AIR CONDITIONING
RR
G
Y
W1
W2
C
G
W1
W2
Y
C
Y/Y2
Y1
O
HUM
X/L
COM
HUMIDISTAT
*
Air Handler Control Wiring
Typical A/C with Electric Heat Applications