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OPERATIONAL INFORMATION
Five-minute Compressor Timeguard
This timer prevents the compressor from starting unless it has been off for at least 5 minutes. It can be defeated for 1 cycle by simultaneously
pressing the FAN button and the UP button.
Fifteen-minute Cycle Timer
This timer prevents the start of a heating or cooling cycle until at least 15 minutes after the last start of the same cycle. Its function is to assure
that equipment is not cycled more than 4 times per hour. This timer is defeated for 1 cycle when the desired temperature is manually changed.
It can also be defeated for 1 cycle by simultaneously pressing the FAN button and the UP button.
Fifteen-minute Staging Timer
In multistage heating or cooling, this timer prevents any higher stage from turning on until the preceding stage has been on for 15 minutes.
This timer is defeated if the temperature error is greater than 5°F (usually due to a large change in desired temperature).
Three-minute Minimum On Time
In normal operation, when a stage turns on, it will not turn off for a minimum of 3 minutes.
Heat/Cool Set Points (Desired Temperatures)
A minimum difference of 2 degrees is enforced between heating and cooling set points. This is done by allowing one setting to "push" the other,
to maintain this difference.
Auto Changeover
When the auto changeover mode is selected, a change from heat to cool (or vice versa) will not occur until an opposite mode demand has existed
continually for 20 minutes. If the set point is changed, the 20 minute requirement is deleted.
Emergency Heat Mode
When emergency heat mode is selected, all Y signals are locked out and W becomes energized upon a call for heat.
Power On Check
When AC power is first applied, all icons of the display are turned on for a few seconds, and the temperature display reads "dF" if it is set for
single speed compressor (DIP switch D set to OFF), or "d2" if it is set for 2-speed compressor (DIP switch D set to ON).
Error Codes
-- - If thermostat cannot properly read room temperature, the room temperature display will indicate "--" and thermostat will enter FREEZE
PROTECT mode. When outdoor temperature is below 50°F furnace will operate for sufficient time every half hour to keep home from
freezing. The ON time is given by the formula: Minutes ON equals 15 minus (outdoor temperature in ˚F divided by 4).
E2 - If the AC line voltage drops below a minimum (brownout) level, all outputs are turned off and the display indicates E2. If the AC line
voltage disappears completely, the display will immediately go blank.
E3 - If thermostat cannot properly read outdoor temperature, E3 will alternate with room temperature on the room temperature display and the
outdoor temperature will read "--" (2 dashes).
E6 - If defrost timer continues for longer than 15 minutes, E6 will be displayed. Check heat pump wiring or for a failed heat pump defrost
control.
Auxiliary Heat Icon
This icon is displayed when the furnace is operating.
Smart Recovery
With Smart Recovery selected, the transition out of a heating setback begins 90 minutes before the selected recovery time and gradually adjusts
room temperature so that the desired temperature will be achieved at the selected recovery time.
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Thermostat Troubleshooting
SYMPTOM
WHAT TO CHECK
Blank LCD
Check for 24 VAC between R and C at terminal connections. Both R and C must be con-
nected for proper operation.
"--" on temperature display
Temperature sensor reading out of range. Check sensor for damage. If recycling power
does not clear display, thermostat should be replaced.
"E2" on temperature display
Brownout condition or too low of voltage to thermostat. Double check wiring and check for
24 VAC between R and C. E2 will clear 15 seconds after proper voltage is restored.
"E3" on temperature display
Outdoor temperature sensor reading out of range. An attempt to read outdoor temperature
results in "--" on display. Check for shorted, open, or failed outdoor temperature sensor.
"E6" on temperature display
System stuck in defrost. Check wiring and heat pump defrost control board.
"Clean Filter" on temperature display
After the selected number of hours of blower operation "clean filter" will display on LCD.
This is to remind the homeowner to "check" filter. Press "reset filter" button to clear dis-
play and reset timer to 0.
Cooling will not come on
Select COOL mode. Decrease cooling set point to 10 degrees below room temperature.
Simultaneously press FAN and UP buttons to defeat timers. Check for 24 VAC at Y/Y2
terminal. If present, thermostat is OK and problem is with equipment or wiring. If not
present, replace thermostat.
Heating will not come on
Select HEAT mode. Increase heating set point to 2 or 3 degrees (not more) above room
temperature. Simultaneously press FAN and UP buttons to defeat timers for 1 cycle.
Check for 24 VAC at Y/Y2 terminal (single-speed HP) or Y1/W2 terminal (2-speed HP)
after 10 seconds. Increase heating set point to 7 or 8 degrees above room temperature.
Check for 24VAC at W/W1 terminal.
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