Furnace Not Heating
PriorityFurnace not producing heat or failing to maintain temperature.
A furnace that will not heat has several potential causes ranging from simple fixes to major repairs. Always prioritize safety with gas furnaces. If basic checks do not resolve the issue, professional diagnosis identifies whether the problem is ignition, airflow, gas supply, or control-related. Modern furnaces have safety features that prevent operation when problems are detected.
Symptoms to Look For
Possible Causes
What You Can Check
Before calling for service, try these safe checks that may resolve simple issues:
When to Call a Professional
If you smell gas, leave immediately and call your gas utility. For non-emergency issues like ignition failures, repeated shutdowns, or no heat despite DIY checks, professional service is needed. Do not attempt to repair gas components yourself.
Need HVAC service?
Call (650) 540-7205 or book online.
Prevention Tips
Frequently Asked Questions
Why does my furnace blow cold air?
Several causes: thermostat set to fan only instead of heat, pilot or ignition failure preventing burner operation, overheating causing safety shutdown, or gas supply issues. Check thermostat first, then call for service if needed.
How often should furnace filters be changed?
Every 1-3 months depending on filter type and household factors like pets and allergies. During heating season, monthly checks are recommended. A dirty filter is a common cause of heating problems.
Is a furnace not heating an emergency?
In cold weather, yes. In Bay Area mild winters, it is typically urgent but not life-threatening. However, gas odors or carbon monoxide detector alerts are always emergencies requiring immediate attention.
Browse Other Issues
Ready to Get Started?
Contact us today for expert HVAC service throughout the Bay Area.