Common Issue
Furnace Blowing Cold Air?
When your furnace runs but doesn't produce heat, here's what might be wrong and when to call for help.
Get Same-Day DiagnosisCommon Causes & Solutions
Thermostat Set to FAN Only
DIY FixThe fan is running continuously but the heating cycle isn't activated.
Solution: Switch thermostat from 'FAN' to 'AUTO' and set to heating mode.
Clogged Air Filter
DIY FixRestricted airflow causes overheating and safety shutdown.
Solution: Replace the air filter with a new one of the correct size.
Pilot Light or Ignition Problem
Call ProThe burners aren't igniting to heat the air.
Solution: Professional diagnosis of ignition system required.
Gas Supply Issue
Call ProGas valve closed or gas supply interrupted.
Solution: Check gas valve position; call professional if issue persists.
Flame Sensor Dirty
Call ProDirty sensor can't detect flame, causing safety shutdown.
Solution: Professional cleaning or replacement of flame sensor.
Overheating and Limit Switch Tripped
Call ProSafety switch shut down burners due to overheating.
Solution: Professional diagnosis to identify overheating cause.
When to Call a Professional
- DIY fixes didn't resolve the issue
- You smell gas near the furnace
- Error codes are displayed
- Problem keeps recurring
- Furnace is making unusual noises
Related Issues
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