Use and Care Manual

8
Troubleshooting
If you have difficulty with your thermostat, please try the following suggestions.
Most problems can be corrected quickly and easily.
Display is
blank
• Check circuit breaker and reset if necessary.
• Make sure power switch for heating & cooling system is on.
• Make sure furnace door is closed securely.
• Make sure fresh AA alkaline batteries are correctly installed
(see page 6).
Heating
or cooling
system does
not respond
• Press Mode button to set system Heat (see page 2).
Make sure the desired temperature is set higher than the
inside temperature.
• Press Mode button to set system Cool (see page 2).
Make sure the desired temperature is set lower than the
inside temperature.
• Check circuit breaker and reset if necessary.
• Make sure power switch for heating & cooling system is on.
• Make sure furnace door is closed securely.
• Wait 5 minutes for the system to respond.
Temperature
settings do
not change
• If display says “unlock”; see page 5. If not, verify you are
in the correct mode (heat, cool, em heat or auto); see page
2.
• If you are in the correct mode, but you cannot set the heat
from 40 °F to 90 °F (4.5 °C to 32 °C), or set the cool from
50 °F to 99 °F (10 °C to 37 °C), you may have range-stops
restricting your setting. Check with the installer to see if
they set range-stops.
“Cool On” or
“Heat On” is
flashing
• Compressor protection feature is engaged. Wait 5 minutes
for the system to restart safely, without damage to the
compressor (see page 5).
Electrical Ratings
Terminal Voltage (50 Hz/60 Hz) Running Current
W Heating 20 Vac - 30 Vac 0.02 A - 1.0 A
W2 (Aux) Heating (TH4210U only) 20 Vac - 30 Vac 0.02 A - 1.0 A
E Emergency Heat (TH4210U only) 20 Vac - 30 Vac 0.02 A - 0.5 A
Y Compressor Stage 1 20 Vac - 30 Vac 0.02 A - 1.0 A
G Fan 20 Vac - 30 Vac 0.02 A - 0.5 A
O/B Changeover 20 Vac - 30 Vac 0.02 A - 0.5 A
L/A Input 20 Vac - 30 Vac 0.02 A - 0.5 A