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Cindy SimsSep 3, 2025
What does “Filter” mean on Honeywell T8635L Thermostat?
- AApril KhanSep 4, 2025
The “Filter” display along with the green LED indicates that the filter has expired. No answer.
To Next PageTo Next PageWhat does “Filter” mean on Honeywell T8635L Thermostat?
The “Filter” display along with the green LED indicates that the filter has expired. No answer.
Why does my Honeywell T8635L display not come on?
The display might not be working because the thermostat isn't getting power. Ensure the thermostat is properly mounted and latched onto the wallplate. Also, check the circuit breaker and reset it if it has tripped. Examine the fuse at the fuse box and replace it if it's blown. Finally, confirm that the system switch at the equipment is in the On position.
Why is the red LED lit on my Honeywell T8635L Thermostat?
The red LED indicates that the heat pump has signaled the thermostat about a problem. If you have a multistage heat pump, move the System switch to the Em.Ht setting. See Heat Pump Operating Instructions or no answer.
Why is my Honeywell Thermostat cooling not working, but the system indicator is on?
If the cooling does not come on, but the system on indicator is displayed on your Honeywell Thermostat, it may be due to a communication issue or incorrect wiring. End and repeat the call for cool. Check the Flash Com OK LED on the W8635 EIM or W8835 while the call is being made. If the Flash Com OK LED does not blink, check communication bus wiring. If the Flash Com OK LED blinks correctly, check that 24 Vac is present at Y1 or W1/Y1 terminal, depending on which EIM is being used. If 24 Vac is not present, check R to Rc and/or Rh connections. If the R to Rc and/or Rh connections are good, replace the W8635 EIM or W8835.
Why is my Honeywell Thermostat heating not working, but the system indicator is on?
If the heating does not come on, but the system on indicator is displayed on your Honeywell Thermostat, it may be due to a communication issue or incorrect wiring. Try ending the call and repeating it. Check the Flash Com OK LED on the W8835 or W8635 EIM during the call. If it doesn't blink, check the communication bus wiring. If it blinks correctly, check for 24 Vac at the W1 or W1/Y1 terminal, depending on the equipment module. If 24 Vac is absent, check the R to Rh connection. If the connection is good, the W8835 or W8635 EIM may need replacement.
Why is the outdoor temperature not displayed or incorrect on my Honeywell Thermostat?
The outdoor temperature may not be displayed, because the installer did not activate this option or the outdoor sensor is connected incorrectly. No answer.
What does “no com” mean on my Honeywell T8635L?
The “no com” message indicates that the thermostat can't communicate with the equipment interface module at the furnace. Try turning the power off and then on to your furnace. If the problem continues, no answer.
What does 'wait' mean on my Honeywell T8635L Thermostat, and why isn't cooling or heating starting?
If “wait” is displayed and the call for Cool (or Heat when used in a heat pump application) has not started on your Honeywell Thermostat, compressor protection is likely active. This feature can be set from 0 to 5 minutes to prevent compressor damage from rapid cycling. Wait until the compressor protection period expires. To bypass this during installation, refer to the Installer System Test section.
How to fix a Honeywell T8635L when the display does not come on?
If the Honeywell Thermostat display doesn't come on, the issue is likely a power problem. First, ensure the thermostat is correctly mounted and latched on the wallplate. Then, check the circuit breaker and reset it if it has tripped. Next, verify the fuse in the fuse box and replace it if blown. Also, check that the power switch at the equipment is in the On position. Finally, inspect the wires on terminals 2 and 3 for 24 VAC; replace any broken wires. If power is present, the thermostat may need replacement.
What to do if my Honeywell T8635L Thermostat cooling does not come on?
If the cooling isn't working, first, make sure the setpoint is below the room temperature. Second, check that the System selection is set to Cool. Finally, if the cooling setpoint is above room temperature, allow five minutes for the system to respond, during which the thermostat will display “Wait”.
General| Power Source | Battery or Hardwired |
|---|---|
| Programmable | Yes |
| Power Method | Battery or Hardwired |
| Mounting | Wall Mounted |
| Color | White |
| Display | Digital |
| Temperature Differential | 1°F |
| Control Type | Digital |
