Honeywell Standard Non-Programmable Thermostat (CT5X) Owner's Manual

7

69-1525—2

See Table 3 to troubleshoot your thermostat.

Heating/cooling 
equipment does not 
operate.

No power to the 
thermostat.

Check power to heating/cooling equipment:
— On/Off switch.
— Fuse or circuit breaker.
— Loose 24V connection: at thermostat; at furnace/air 

conditioner.

— Incorrect wiring; check appropriate wiring diagram.

System switch on 
thermostat not in 
correct position.

Reset System switch.

Thermostat minimum-
off times operating for 
cooling.

Wait five minutes.

Incorrect wiring.

Check wiring.

Heating/cooling 
equipment not 
operating.

Consult equipment manfacturer instructions.

Partial display.

Thermostat not 
operating.

Replace thermostat.

Remained in customize 
mode.

See Customize Your Thermostat section to exit this mode.

No display.

No power to thermostat.

Check power to thermostat.

Thermostat mounted 
incorrectly on wallplate.

See Mount Thermostat to Wallplate section.

Temperature display 
is incorrect.

Thermostat is 
configured for °F or °C.

Reconfigure the display. See Customize Your Thermostat 
section for instructions to change the display.

Cannot change 
temperature setting.

The upper or lower 
temperature limits were 
reached.

Check the temperature setpoints; temperature setting range is 
40°F (4°C) to 99°F (37°C).

Snowflake is 
flashing.

Cooling equipment 
turns on after delay.

Wait approximately five minutes after the indicator starts flashing 
and then check the registers.

System on indicator 
(flame=heat) is 
displayed, but no 
warm air is coming 
from the registers.

Heating equipment 
turns on the fan when 
the furnace has 
warmed up to a 
setpoint.

Wait a minute after seeing the on indicator and then check the 
registers. If still no heat is coming from the registers, call your 
local heating and/or cooling contractor.