PRO TH3110D Non-programmable Digital Thermostat
11
In case of difficulty

If you have difficulty with your thermostat,please try the suggestions below. Most

problems can be corrected quickly and easily.

Display is blank • Check circuit breaker and reset if necessary.
• Make sure heating & cooling power switches are on.
• Make sure equipment door is securely closed.
• If battery powered, make sure fresh AA alkaline batteries are installed.
Temperature
settings do not
change
Make sure heating and cooling temperatures are set to acceptable ranges:
• Heat: 40° to 90°F (4.5° to 32°C).
• Cool: 50° to 99°F (10° to 37°C).
Fan does not
turn on in a
call for heat
• Make sure the Fan Operation switch is set to the proper system.
Heating system
does not respond
(“Heat On”
appears on
screen)
• Check for 24 Vac at the equipment on the secondary side of the trans-
former between power and common. If voltage is not present, check the
heating equipment to find the cause of the problem.
• Check for 24 Vac between the heat terminal (W) and the transformer
common. If 24 Vac is present, the thermostat is functional. Check the
heating equipment to find the cause of the problem.
• Check for loose or broken wires between the thermostat and the heating
equipment.
Cooling system
does not respond
(“Cool On”
appears on
screen)
• Check for 24 Vac at the equipment on the secondary side of the trans-
former between power and common. If voltage is not present, check the
cooling equipment to find the cause of the problem
• Check for 24 Vac between the cooling terminal (Y) and the transformer
common. If 24 Vac is present, the thermostat is functional. Check the
cooling system to find the cause of the problem.
• Check for loose or broken wires between the thermostat and the cooling
equipment.
“Cool On” or
“Heat On”
is flashing
• Compressor protection timeout is engaged. Wait 5 minutes for the
system to restart safely, without damage to the compressor.
“Heat On” is
not displayed
• Set the System switch to Heat, and set the temperature level above the
current room temperature.
“Cool On” is
not displayed
• Set the System switch to Cool, and set the temperature level below the
current room temperature.