Honeywell Smart Thermostat Not Controlling HVAC

Honeywell Home thermostats including the T10 Pro, T5+, T9, and T6 Pro provide smart temperature control. This guide covers common HVAC control and connectivity issues.

Common Symptoms

• HVAC not turning on when called
• System short cycling
• Temperature not matching setpoint
• Thermostat showing offline
• Smart Room Sensors not reporting (T9/T10)
• Schedule not being followed

System Not Responding

1. Check Thermostat Power

• Verify display is lit and responsive
• Battery backup may indicate power issue
• Check C-wire connection for continuous power
• Inspect wiring at thermostat and HVAC equipment

2. Verify Equipment Power

• Check circuit breakers for furnace and AC
• Ensure furnace door is properly closed
• Look for diagnostic lights on HVAC control board
• Verify outdoor unit has power

3. Check Mode Settings

1. Press Mode button on thermostat
2. Select Heat, Cool, or Auto as needed
3. Verify setpoint is set to trigger system
4. Wait for system response (may take minutes)

WiFi Connectivity (T5+, T9, T10)

Connecting to WiFi

1. On thermostat, go to Menu > WiFi Setup
2. Select your network from the list
3. Enter password using on-screen keyboard
4. Wait for connection confirmation

Connection Issues

• Ensure 2.4GHz network is available (required)
• Check signal strength at thermostat location
• Restart router if multiple devices have issues
• Try forgetting and re-adding network

Z-Wave Issues (T6 Pro Z-Wave)

Adding to Z-Wave Hub

1. Put Z-Wave hub in inclusion mode
2. On thermostat, go to Menu > Installer Setup > Z-Wave
3. Select Include
4. Wait for hub to discover thermostat

Not Responding to Hub

• Check Z-Wave hub is online and functioning
• Exclude and re-include if connection is unstable
• Verify thermostat is within Z-Wave range
• Run Z-Wave network repair if available

Smart Room Sensor Issues (T9, T10)

Sensor Not Pairing

1. Pull battery tab on new sensor or insert fresh batteries
2. On thermostat, go to Menu > Smart Room Sensors
3. Select Add Sensor and follow prompts
4. Keep sensor within 3 feet during pairing

Sensor Showing Offline

• Check sensor battery level in app
• Move sensor closer to thermostat
• Remove and re-add sensor if issues persist
• Check for interference from metal objects

Schedule Problems

Not Following Schedule

• Verify schedule is enabled in app
• Check for manual temperature holds
• Ensure time and date are correct on thermostat
• Disable Geofencing if causing unexpected changes

Geofencing Issues

• Check phone location permissions for Honeywell app
• Verify geofence radius is appropriate
• All household members may need location sharing

App Control Issues

App Not Connecting

1. Verify thermostat is online (check display)
2. Force close and reopen Honeywell Home app
3. Check phone internet connection
4. Log out and back into Honeywell account

Temperature Calibration

If temperature reading is off:

1. Go to Menu > Installer Setup > Temperature Offset
2. Adjust offset based on comparison with accurate thermometer
3. Offset typically ranges from -3°F to +3°F

Factory Reset

1. Go to Menu > Reset > Factory Reset
2. Confirm reset
3. Thermostat will restart with default settings
4. Re-run initial setup and WiFi/Z-Wave configuration

When to Contact Support

Contact Honeywell support or HVAC technician if:

• HVAC equipment won't respond at all
• Wiring issues suspected
• Continuous error codes
• System damaging short-cycling behavior