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 mode button and the INCREASE TEMPERATURE 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 mode button and the INCREASE TEMPERATURE button.
FIFTEEN-MINUTE STAGING TIMER
In multistage heating or cooling, this timer prevents any higher stage from turning on until the preceeding stage has been on for 15 minutes. This
timer is defeated if the temperature error is greater than 5 degrees (usually due to a large change in desired temperature).
TWO-MINUTE MINIMUM ON TIME
In normal operation, when a stage turns on, it will not turn off for a minimum of 2 minutes.
HEAT/COOL SETPOINTS (DESIRED TEMPERATURES)
A minimum difference of 3 degrees is enforced between heating and cooling desired temperatures. 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
for 20 minutes. If the setpoint is changed, the 20 minute requirement is deleted.
POWER ON CHECK
When AC power is first applied, all segments of display are turned on for a few seconds. Following this, the temperature display reads dF for a
few seconds to indicate that it is a dual fuel thermostat.
ERROR CODES
E1 - If thermostat cannot properly read room temperature, the room temperature display will indicate E1 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. This condition will
remain for 15 seconds after proper line voltage is restored. If the AC line voltage disappears completely, the display will immediately go
blank.
E3 - If thermostat cannot properly read outdoor temperature E3 will be displayed in place of room temperature. The thermostat will continue to
operate, but will only use furnace in HEAT mode.
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 a fixed time period before the selected recovery time and gradually
adjusts room temperature so that the desired temperature will be achieved at the selected recovery time. The fixed time period is 1 hr for furnaces
and 1.5 hrs for heat pumps.
THERMOSTAT TROUBLESHOOTING
SYMPTOM
WHAT TO CHECK
No LCD on temperature display
Check for 24 VAC between R and C at terminal connections. Both R and C must be connected for proper opera-
tion.
″
Trouble
″
on temperature display
Outdoor temperature sensor reading out of range. An attempt to read outdoor temperature results in
″
--
″
on dis-
play. Check for shorted, open, or failed outdoor temperature sensor.
″
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.
″
E1
″
on temperature display
Temperature sensor reading out of range. Check sensor for damage. If recycling power does not clear display,
thermostat should be replaced.
″
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 ho-
meowner to
″
check
″
filter. Press
″
reset filter
″
button to clear display and reset timer to 0.
Cooling will not come on
Select COOL mode. Decrease cooling setpoint to 10 degrees below room temperature. Simultaneously press FAN
and INCREASE TEMPERATURE buttons to defeat timers. Check for 24 VAC at Y/Y2 terminal. If present, thermo-
stat is OK and problem is with equipment or wiring. If not present, replace thermostat.
Heating will not come on
Select HEAT mode. Increase heating setpoint to 2 or 3 degrees (not more) above room temperature. Simulta-
neously press FAN and INCREASE TEMPERATURE 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) within 10 seconds. Increase heating setpoint to
7 or 8 degrees above room temperature. Check for 24VAC at W/W1 terminal (single-speed HP) or Y/Y2 terminal
(2-speed HP) within 2 minutes. After 2 minutes check for 24VAC at Y1/W2 terminal (single-speed HP) or W/W1
terminal (2-speed HP).
—7—
