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Furnace Not Heating

Furnace running but no heat? Or not running at all? Find the cause and solution here.

This may need urgent attention

Need immediate help? Our technicians are available 24/7.

Call Now: (650) 397-7060

Common Symptoms

If you're experiencing any of these symptoms, you may have this problem:

Furnace runs but blows cold air
House won't warm up
Furnace won't turn on at all
Heat is weak or inconsistent

Possible Causes & Solutions

Thermostat Settings

DIY Possible

Check thermostat is set to HEAT and temperature is correct

Dirty Air Filter

DIY Possible

Replace clogged air filter

Pilot Light Out

DIY Possible

Relight pilot light following manufacturer instructions

Ignition Problems

Pro Required

Professional ignitor or sensor cleaning/replacement

Gas Supply Issues

DIY Possible

Check gas valve is open, call gas company if needed

Blower Motor Problems

Pro Required

Professional motor repair or replacement

When to Call a Professional

While some issues have DIY solutions, HVAC systems are complex. Call a professional when:

  • DIY solutions don't resolve the problem
  • The issue involves electrical components
  • You smell gas or burning odors
  • The problem returns after temporary fixes
  • Your system is under warranty (DIY repairs may void it)
Call San Jose HVAC Pros: (650) 397-7060

Related Services

Furnace Repair

Fast, reliable furnace repair to restore your heat

$89-$600+

Furnace Maintenance

Annual furnace tune-up for safe, efficient heating

$89-$199

Emergency HVAC

Round-the-clock emergency HVAC repair service

$150+ service call

Frequently Asked Questions

Why won't my furnace turn on?

Common causes include a tripped circuit breaker, thermostat issues, pilot light problems, or a faulty ignition system. We can diagnose all furnace issues.

My furnace is making strange noises. What does it mean?

Different noises indicate different issues: banging may mean delayed ignition, squealing could be a belt issue, and rumbling might indicate a burner problem.

How often should I change my furnace filter?

Standard filters should be changed every 1-3 months depending on usage, pets, and allergies. Higher-quality filters may last longer but check monthly.

Is a cracked heat exchanger dangerous?

Yes, a cracked heat exchanger can leak carbon monoxide, which is dangerous. If suspected, turn off your furnace immediately and call for service.

Related Problems

Won't Ignite

Furnace trying to start but won't ignite? This is a common issue with several possible causes.

Noisy Furnace

Strange sounds from your furnace? Learn what different noises mean and when to call for help.

Furnace Cycling

Furnace keeps turning on and off? This wastes energy and could damage your system.

Need Help With No Heat?

San Jose HVAC Pros technicians are ready to diagnose and fix your problem

Call Now: (650) 397-7060 Schedule Service
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