Question 1

the fan won't turn on when it's supposed to, either auto or when i manually set it to on.

Accepted Answer

DIAGNOSIS The G terminal signal (Fan control) is not being sent or received. This is a wiring, configuration, or equipment issue. FIX First, verify the wiring. Remove the thermostat from its base. Confirm a wire is securely inserted in the G terminal on both the thermostat and the baseplate. Next, test the fan manually. On the thermostat, press the FAN button until the display reads 'ON'. You should hear a click from the thermostat. Then, go to your furnace and listen for a second click from the control board relay. If you hear both clicks but the blower doesn't start, the issue is at the furnace. IF THAT DIDN'T WORK The problem is likely a faulty blower motor, control board relay for the fan, or a disconnected wire at the furnace. At the furnace control board, locate the G terminal. With the thermostat calling for FAN ON, use a multimeter to check for 24VAC between G and C. If voltage is present, the blower motor or its capacitor has failed. If no voltage, the thermostat wire between the G terminals is broken. HEADS UP In 'Auto' mode, the fan only runs during a heating or cooling cycle. There is a built-in delay on most systems. Wait up to 90 seconds after the furnace or AC starts for the blower to engage. This is normal operation.

Question 2

my schedule keeps disappearing or resetting on its own. i set it and a day later it's gone.

Accepted Answer

DIAGNOSIS Schedule corruption or conflict. This occurs when schedules are changed from multiple sources (device, app, website) or after a power interruption that causes memory issues. FIX Set the schedule from one source only. Use either the thermostat interface OR the Total Connect Comfort app/website. Do not mix. To reset, on the thermostat, press Menu > Schedule. Select Clear Schedule for both Wake and Leave periods. Re-enter your complete weekly schedule directly on the thermostat. Ensure you press DONE after each day and period. Finally, confirm the System Mode (Menu > Preferences > System) is set to Heat, Cool, or Auto—not OFF or EM Heat. IF THAT DIDN'T WORK A weak or missing C-wire (common wire) can cause memory loss during short power cycles. Remove the thermostat from its base and verify a wire is connected to the terminal labeled 'C'. If no C-wire is present, the thermostat relies on power-stealing, which can be unstable and corrupt settings. Installing a C-wire or a Honeywell C-wire adapter is the solution. HEADS UP If you use the 'Hold' function (pressing Temperature to temporarily override), ensure you understand the hold type. A 'Temporary Hold' reverts to schedule at the next programmed change. A 'Permanent Hold' cancels the schedule until you manually select 'Run Schedule'.

Question 3

how do i fix a temperature reading that's way off? it says 72 but my room feels like 65.

Accepted Answer

DIAGNOSIS Inaccurate temperature sensing. This is caused by heat generated internally by the device or by an external source influencing the sensor. FIX Apply a temperature offset to calibrate the reading. Press Menu > Preferences > Temperature Offset. The default is 0°. If the thermostat reads higher than actual, set a negative offset (e.g., -3°). If it reads lower, set a positive offset. Adjust in 1-degree increments, wait 2 hours for stabilization, and verify with a known-accurate thermometer placed next to the thermostat. IF THAT DIDN'T WORK The thermostat's location is causing the error. Ensure it is mounted on an interior wall, away from direct sunlight, drafts, doorways, heat-producing electronics (like TVs or lamps), and air vents. Relocating the thermostat to a neutral location is the permanent solution, which may require running new low-voltage wire. HEADS UP The thermostat generates a small amount of its own heat. This is why the offset feature exists. Do not install it on a wall with in-wall electrical conduits that generate heat, as this will skew readings permanently.

Question 4

the app says my thermostat is offline but the screen on the wall looks fine and is working.

Accepted Answer

DIAGNOSIS A communication failure between the thermostat and the Honeywell cloud servers, despite local operation. The thermostat's Wi-Fi module may have lost its upstream connection. FIX First, check the thermostat's connection status. On the device, press Menu > Wi-Fi. The icon should be solid, not flashing. If flashing, it has lost the local network. Follow reconnection steps. If the icon is solid, the issue is upstream. Restart your home router and modem. Wait 5 minutes for full reboot. Then, on the thermostat, go to Menu > Wi-Fi > Disconnect. Wait 30 seconds, then select Connect and re-enter your credentials to force a fresh cloud handshake. IF THAT DIDN'T WORK There may be a service outage with Honeywell's Total Connect Comfort service. Check the status page on the Honeywell Residential website. If services are operational, a factory reset of the thermostat may be required (Menu > Preferences > Factory Reset). You will need to reconfigure all settings. HEADS UP After reconnecting, allow up to 15 minutes for the thermostat to fully synchronize with the cloud servers and appear online in the app. Do not repeatedly disconnect/reconnect during this period.

Question 5

why is my thermostat losing its wifi connection every few days? i have to keep reconnecting it.

Accepted Answer

DIAGNOSIS Intermittent Wi-Fi dropouts. This is usually caused by an unstable router connection, IP address conflicts, or interference. FIX Assign a static IP address to the thermostat within your router's settings. This prevents DHCP lease expiration from causing drops. Log into your router's admin page. Find the connected device list, identify the thermostat by its MAC address (found under Menu > Wi-Fi > About), and assign it a reserved IP address outside the DHCP pool. Reboot the router and thermostat. IF THAT DIDN'T WORK The issue may be signal interference or router firmware. Ensure the thermostat is not on a shared wall with major appliances. Change your router's 2.4 GHz channel to 1, 6, or 11 to avoid congestion from neighbors. Check your router manufacturer's website for firmware updates and install them. HEADS UP Some power-saving features on modern routers can aggressively disconnect idle devices. In your router's advanced Wi-Fi settings, look for options like "Airtime Fairness," "Smart Connect," or "Wi-Fi Multi-Media" and disable them for testing.

Question 6

i can't get my honeywell rth6580wf to connect to my wifi. it keeps failing.

Accepted Answer

DIAGNOSIS The thermostat is failing to join your wireless network. Common causes are incorrect credentials, a weak signal, or incompatible network security settings. FIX Follow this checklist. First, ensure your router is broadcasting a 2.4 GHz network. This model does not support 5 GHz. During setup, select your 2.4 GHz SSID. Second, enter the Wi-Fi password precisely. Passwords are case-sensitive. Third, check signal strength. The thermostat requires a strong signal. Use a phone to check bars at the thermostat location. If weak, consider a Wi-Fi extender. Fourth, temporarily disable any MAC address filtering on your router until setup is complete. IF THAT DIDN'T WORK Your router's security protocol may be incompatible. The RTH6580WF supports WPA/WPA2-Personal (AES/TKIP). It does not support WPA3 or enterprise-level security. Access your router's settings and ensure the 2.4 GHz band is using WPA2-Personal (AES). Try the connection again. HEADS UP A factory reset of the thermostat's network settings can clear a corrupted configuration. Press and hold the Fan and Up arrow buttons for 5 seconds until the Wi-Fi icon flashes. This clears only network info, not your schedule or settings.

Question 7

my honeywell wifi thermostat screen is just blank, no backlight, nothing. it was working yesterday.

Accepted Answer

DIAGNOSIS The thermostat has no power. The most likely cause is a tripped system fuse or a blown 24VAC transformer due to a short in the low-voltage wiring. FIX First, check the HVAC system's power. Go to your main electrical panel. Find the breaker for your furnace or air handler. Ensure it is ON. Next, locate the furnace/air handler itself. Open the service panel. Find the low-voltage fuse, typically a 3-amp or 5-amp automotive-style blade fuse. Remove and inspect it. If the fuse is blown, replace it with an identical fuse. Re-mount the thermostat base. If the screen lights up, the short was likely momentary. IF THAT DIDN'T WORK The 24VAC transformer inside the HVAC unit may have failed or been tripped. At the furnace, locate the transformer (usually a small, square or rectangular component with wire terminals). Use a multimeter to check for ~24VAC between the R (power) and C (common) terminals. If you read 0VAC, the transformer needs replacement by a technician. HEADS UP A blown fuse often indicates a wiring short. Before replacing the fuse, ensure no thermostat wires are touching each other or the metal wall plate. A recurring blown fuse points to a persistent short that requires professional diagnosis.

Honeywell Home RTH6580WF WiFi Thermostat

Other Thermostats