1
Operation
The display indicates room temperature and the word ROOM is shown on the LCD until the temperature selector is pressed; at that
time the display temporarily indicates the setpoint temperature and the word SET is shown on the LCD. Each time the UP arrow
is pressed, the setpoint will increase. Each time the DOWN arrow is pressed, the setpoint will decrease. Once the temperature
selector button is no longer pressed for a few seconds, the room temperature will again be displayed, and the word ROOM will be
displayed on the LCD.
In electric heat mode, if the heat pump is unable to satisfy the thermostat, the heat pump goes into
lockout. DIFF will display on the thermostat LCD indicating second stage heating is required to
satisfy the thermostat.
In gas heat mode, the gas furnace will provide the only source of heat and the heat pump is locked
out.
Refer to truth table (below) for a more
detailed listing of operation sequence.
Note:
The temperature is displayed in degrees Fahrenheit as a factory set default (see Figure 2 on Page 7). To display in degrees
Celsius, move the jumper marked “F” and “C” to bridge between middle pin and position “C.”
Mode Switch
Fan Switch #1
Fan Switch #2
Calling
Operation
1
Cool
Auto
Lo
No
No functions occur in this mode
2
Cool
Auto
Lo
Stage 1
1° Above Set
ID fan low, compressor #1 and OD blower low cycle as needed
3
Cool
Auto
Lo
Stage 2
2° Above Set
ID fan low, compressor #1 and #2 and OD blower high cycle as needed
4
Cool
On
Lo
No
ID fan low continuous
5
Cool
On
Lo
Stage 1
1° Above Set
ID fan low continuous, compressor #1 and OD blower low cycle as needed
Operation Chart
The chart below shows the system functions with the 6535-344• thermostat. After the entire air conditioning system (and
furnace system) is installed, check each position function.
6535-344* 2-Stage Heat Pump Thermostat Truth Table
