Carrier P274-0200-C - Manual (Page 2)

Battery Changeout — if tlie installation requires the
usage of batteries, the batteries will require replacement eveiy
12 months.
Open thermostat door and slide the batteiy compartment
door to the right. Remove two AA alkaline batteries. Instiill
two new AA alkiiline batteries following the polarity markings
(+ / -) on the thermostat.
NOTE: If installation is hard-wired, batteries are not
required and will not need to be replaced.
Error Codes — if the thermostat displays “E2”,
“E3”, or “E4” in the LCD, an error is present. See Table I for
error codes and descriptions.
Table 1 — Error Codes
SYMPTOM WHAT TO CHECK
Blank LCD Check tor 24 vac between R and C at terminal connections or battery.
{2 dashes) 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 sec after proper voltage is restored.
"E3" on temperature display The outdoor temperature sensor is open, not connected, or shorted.
"SERVICE FILTER" on temperature display After the selected number of hour of blower operation "FILTER" will display on LCD. This is
to remind the home owner to "check" the filter. Press RESET FILTER button to clear display
and reset timer to 0.
Cooling will not come on Select COOL mode. Set desired temperature to 10° F below room temperature. Simulta­
neously press FAN and INCREASE TEMPERATURE buttons to defeat timers. Check tor
COOL ON icon and 24 vac at Y (first-stage) terminal. If present, thermostat is okay and
problem is with equipment or wiring. If not present, replace thermostat.
Heating will not come on Select HEAT mode. Set desired temperature to 10° F above room temperature. Simulta­
neously press FAN and INCREASE TEMPERATURE buttons to defeat timers. Check for
HEAT ON and 24 vac at Y (first-stage) terminal (with heat pump) or W/W1 (with air condi­
tioner) terminal. If present, thermostat is okay and problem is with equipment or wiring. If
not present, replace thermostat.