Nest Thermostat Not Heating: 10 Ways to Fix It

Quick Fix

Nest thermostat not heating? Check if the display shows a blinking red light (low battery). If so, remove from base and charge via USB for 2 hours. Also verify the system is set to Heat mode (not Cool or Off), and the target temperature is higher than the current room temperature.

Why Isn’t Nest Heating?

Nest thermostats fail to heat due to low battery, incorrect mode settings, wiring issues, HVAC system problems, WiFi disconnection, or software glitches. The thermostat may also enter a safety mode if it detects wiring problems.

Method 1: Check Mode and Temperature

Basic settings may be wrong.

1. Open Nest app or check thermostat display
2. Verify it’s set to Heat (not Cool or Off)
3. Set target temp higher than current temp
4. Wait 2-3 minutes for system to respond

Method 2: Check Battery Level

Low battery prevents heating operation.

1. On thermostat: Settings > Technical Info > Power
2. Battery should show 3.7V or higher
3. If low, remove from base
4. Charge via USB-C for 2 hours
5. Reattach to base

Method 3: Restart Nest Thermostat

A restart clears software glitches.

1. Press and hold the thermostat ring
2. Hold for 10 seconds
3. Screen will go black
4. Release and wait for restart
5. Try heating again

Method 4: Check HVAC System

The heating system itself may have issues.

1. Go to furnace/air handler
2. Check the power switch is on
3. Check circuit breaker hasn’t tripped
4. Look for error codes on furnace display
5. Check if air filter is clogged (replace if dirty)

Method 5: Check Wiring

Loose or incorrect wiring causes heating failures.

1. Turn off HVAC power at breaker
2. Remove Nest from base
3. Check all wires are firmly inserted
4. Verify correct wire terminals (Rh, W1, C, etc.)
5. Reattach and restore power

Method 6: Check for Error Codes

Nest displays codes for specific issues.

• E73: No power from C wire
• E74: No heating detected
• E195: No power to Rh wire
• Delayed: System protection delay (wait 2-5 min)

Method 7: Disable Schedule/Eco Mode

Scheduled settings may be blocking heat.

1. Open Nest app
2. Tap Schedule and clear all entries
3. Disable Home/Away Assist temporarily
4. Turn off Eco Temperatures
5. Manually set heating temp

Method 8: Factory Reset Nest

Reset clears all settings and software issues.

1. Settings > Reset > All Settings
2. Confirm reset
3. Wait for restart
4. Set up thermostat again
5. Reconfigure heating settings

Method 9: Check C Wire Installation

Missing C wire causes power and charging issues.

1. Check if C (common) wire is connected
2. If no C wire, consider Nest Power Connector
3. Or add a C wire adapter kit
4. Proper power prevents many issues

Method 10: Test Heat Manually

Force the system to heat for testing.

1. In Nest app, go to Equipment
2. Select Test
3. Run heating test
4. Listen for furnace to kick on
5. If nothing, issue is with HVAC, not Nest

FAQ

Why does my Nest say heating but nothing happens?

This usually indicates an HVAC issue, not a Nest problem. Check furnace power, filter, and error codes. The thermostat is sending the signal, but the heating system isn’t responding.

Why does my Nest thermostat keep turning off heating?

This could be Eco mode, scheduled temperatures, or Home/Away Assist. Check these settings in the app. Also verify the target temp is set correctly.

What does “Delayed” mean on Nest thermostat?

Delayed means Nest is protecting your HVAC system from short cycling. It will start heating after 2-5 minutes. This is normal after power outages or thermostat restarts.