Google Nest
Incorrect System Type or Reversing Valve Configuration
Nest thermostat shows heating is on, but air from vents is cool
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Heat pump configured incorrectly in Nest settings, O/B reversing valve energized in wrong mode, W1 and Y1 miswired, Gas furnace not being called for heat
How to Fix / Troubleshooting
Safety first: Turn off power to the HVAC system before changing wiring.
- Identify system type: Confirm whether you have a heat pump or a conventional furnace with AC.
- Review Nest equipment settings: On the Nest, go to Settings > Equipment and verify the correct system type and O/B behavior (energize in heating or cooling) per your heat pump manual.
- Check wiring mapping: Ensure W1 is connected to the furnace heat call and Y1 to the compressor, and that O/B is only used for the reversing valve on heat pumps.
- Test modes: After restoring power, test both heating and cooling to confirm that hot air blows in heat mode and cold air in cool mode.
If configuration changes do not resolve the issue, the reversing valve or furnace controls may require professional diagnosis.
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Repair Difficulty
Medium
3/5
Required Part
Nest Thermostat Base (O/B, W1, Y1 terminals), Heat Pump Reversing Valve
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