27
Scroll compressors are designed to operate in single direction only. Hence, care has to be taken to ensure correct
rotation when the system is operated. Verification of correct rotation is by observing that the suction pressure drops and
discharge pressure rises when compressor run. Reverse rotation results in abnormal sound, as well as, substantially low
current draw and by interchanging power supply wire L1 & L3 will correct this problem.
*
Clogged filter switch not provided
CONTROLS & SEQUENCE OF OPERATION
The operation of the air conditioning unit is controlled by a 24VAC electronic control board.
Mode:
Select the desired mode of operation by continuous press-
ing of the MODE button:
Controls cooling system only (the word COOL will
display for 5 seconds).
Controls heating system only (the word HEAT will
display for 5 seconds).
HEAT/COOL - Controls both systems automati-
cally (the word AUTO will display for 5 seconds).
OFF - Systems will not operate
Cooling:
Select the temperature you want your cooling system to
maintain by pressing and holding the COOLING button
under the or symbols until the desired tempera-
ture is displayed. The control setpoint temperature is dis-
played for 5 seconds.
Heating:
Select the temperature you want your heating system to maintain by pressing and holding the HEATING button under
the or symbols until the desired temperature is displayed. The control setpoint temperature is displayed for 5
seconds.
Fan:
The fan will be energized automatically when the systems are operating but no indication of this on the display. To select
continuous fan operation, press the FAN button and the display will show . This is recommended for electronic air
cleaners and continuous ventilation requirements.
Off
When the word OFF is displayed the heating and cooling systems will not operate. Avoid using the OFF mode during
extremely cold weather to prevent damage from freezing.
Auto:
Selecting this mode of operation will control both heating and cooling systems. The thermostat will automatically switch
from one to the other as determined by the selected temperatures in heating and cooling.
NOTE: The thermostat always maintains a minimum 2
0
F (1
0
C) difference or dead band between the heating and cooling
setpoints.
Celsius / Fahrenheit
Simultaneously press and to switch between Celsius and Fahrenheit temperature display.
Clogged filter switch not provided
Field Wiring
Thermostat
LED 2
LED 1
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W2
24 V
(C)
24 V
L
H
G
T
S
I
Relays
Equipment
Y1
G
W1
Y2
R
2nd stage
Compressor Fault
Clogged Filter
Heating
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24VAC
Cooling
1st stage
Heating
Fan Relay
1st stage
2nd stage
Cooling
Line Voltage
Transformer