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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
When a stage is turned on, it cannot be turned off until it has been on for at least 2 minutes.
Auto Changeover
When the auto changeover mode is selected, a change from heat to cool (or vice versa) will not occur until a 3 degree demand has existed for
20 minutes. If the desired temperature is changed, the 20 minute requirement is deleted, but the 3 degree requirement is preserved.
Power On Check
When AC power is first applied, all segments of the display are turned on for a few seconds. Following this, the temperature display indicates
the model/configuration via the following 2 digit code:
AC—1-speed air conditioner
HP—1-speed heat pump
A2—2-speed air conditioner
H2—2-speed heat pump
HS—1-speed heat pump with 3-stage auxiliary heat.
Error Codes
E1 - If the thermostat cannot properly read room temperature, the display will indicate E1 and all outputs (except the fan if on) will turn off.
This is to prevent operation of the equipment if the thermostat has failed.
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.
Energy Savings Icon
This icon is displayed under these conditions:
1-speed HP heating without auxiliary heat.
2-speed HP on LO or HI speed heating without auxiliary heat.
2-speed HP or AC on LO speed cooling.
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.
SYMPTOM
No LCD on temperature display
"E2" on temperature display
"E1" on temperature display
"Clean Filter" on temperature display
"Trouble" on temperature display
"--" on temperature display
Cooling will not come on
Heating will not come on
OPERATIONAL INFORMATION
Thermostat Troubleshooting
Check for 24 VAC between R and C at terminal connections. Both R and C must be connected for proper opera-
tion.
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.
Temperature sensor reading out of range. Check sensor for damage. If recycling power does not clear display,
thermostat should be replaced.
After 500 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 display and reset timer to 0.
This will indicate a problem with system equipment. 24 VAC is present on the "L" terminal connection.
If the outdoor sensor is open, not connected, or shorted "--" will be displayed.
Select COOL mode. Set desired temperature 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.
Select HEAT mode. Set desired temperature to 10 degrees above room temperature. Simultaneously press FAN
and INCREASE TEMPERATURE buttons to defeat timers. Check for 24 VAC at Y/Y2 (with HP) or W/W1 (with
AC) terminal. If present, thermostat is OK and problem is with equipment or wiring. If not present, replace thermo-
stat.
7
WHAT TO CHECK
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