Furnace Won't Turn On
Furnace won't start? Check power, the thermostat, door switch and error codes, then call for a licensed furnace repair technician in your state.
Furnace Repair services
Each guide below covers one specific winter problem: symptoms, causes, what you can safely check and what a licensed technician does. Prices are explained in the furnace repair cost guide.
Furnace Blowing Cold Air
Furnace running but blowing cold air? Learn the common causes, from the fan setting to flame sensors and limit switches, and get a licensed repair.
Furnace Short Cycling
Furnace turning on and off every few minutes? Short cycling wastes fuel and wears parts. Causes, fixes and when to call a licensed technician.
Ignitor & Flame Sensor Repair
Furnace clicks but won't light, or lights then goes out? Ignitor and flame sensor problems explained, with when to replace and when to clean.
Noisy Furnace Repair
What furnace noises mean: banging on startup, squealing, rattling, humming and clicking. Which ones are urgent, and how they're repaired.
Common winter problems and where to start
| Problem | What usually causes it |
|---|---|
| Runs but blows cold air | Usually an ignition or flame-sensing fault, a tripped limit switch or a thermostat set to FAN ON. See the causes. |
| Won't turn on at all | Power, a door safety switch, a blown control fuse or a failed inducer motor are the usual suspects. Start here. |
| Turns on and off every few minutes | Short cycling points to overheating, a dirty sensor or an oversized furnace. Short cycling explained. |
| Clicks but never lights | A cracked hot-surface ignitor or a gas-valve problem. Ignitor and flame sensor repair. |
| Banging, squealing or rumbling | Delayed ignition, a worn blower bearing or a loose panel each make a different sound. Decode the noise. |
Watch: winter heating explained
Short, silent clips hosted on muse.ai that show what to look for. They play muted and loop.
Coverage map: all 50 states and DC
Pick your state for local winter conditions, common heating fuels and the cities we route calls from. Colors show how severe winters are, based on IECC climate zones.
- Severe cold (IECC 6–8)
- Cold (5)
- Mixed (4)
- Mild (1–3)
How it works
- Call and describe the problem: furnace type, what it's doing and any error-light pattern.
- We connect you with a licensed provider who covers your area and confirms an arrival window.
- The technician tests the ignition sequence, safeties, gas pressure and airflow to find the actual fault.
- You get the repair price before work starts, and decide whether to proceed.
- The furnace is run through full cycles and checked for carbon monoxide and proper venting.
Decision guide
| Situation | Usually repair | Consider replacement |
|---|---|---|
| Furnace age | Under about 15 years | Over about 15–20 years |
| The failed part | Ignitor, sensor, capacitor, limit switch, inducer | Cracked heat exchanger |
| Repair history | First major repair | Repeated repairs in recent winters |
| Comfort | Even heat until this failure | Cold rooms and rising bills for years |
| Next step | Book the repair | Read the cost guide and compare |
Before you call
Have the equipment type, brand and any blinking error code ready, and note what you've already checked. If anyone at home smells gas or a CO alarm sounds, leave the house and call 911 or the gas utility first.
Emberline Furnace Repair is a referral service. Your call is connected to an independent, licensed provider who serves your ZIP code and quotes the job directly. How it works.
Furnace Repair questions, answered
Why is my furnace running but not heating?
The most common causes are a dirty flame sensor that shuts the burners off, a failed ignitor, a tripped high-limit switch from a clogged filter, or the thermostat fan set to ON instead of AUTO. A technician confirms which one by watching the ignition sequence.
Is it safe to keep resetting my furnace?
No. Repeated resets can flood the burners with gas on some models and mask a safety problem. If the furnace locks out more than once, leave it off and have it checked.
How long does a typical furnace repair take?
Most single-part repairs, such as an ignitor, flame sensor, capacitor or limit switch, take one to two hours once the technician is on site. Inducer motors, control boards and gas valves can take longer if the part has to be ordered.
Can a furnace cause carbon monoxide poisoning?
Yes. A cracked heat exchanger, blocked flue or poor combustion can release carbon monoxide. Keep working CO alarms on every level, and if one sounds, leave the home and call 911 or your gas utility.
What do the blinking lights on my furnace mean?
Most modern furnaces flash a diagnostic code on the control board. The code chart is usually printed inside the blower door. Note the pattern before you call; it speeds up the diagnosis.
Should I repair or replace an old furnace?
If the furnace is under about 15 years old and the problem is a single part, repair is usually the better value. A cracked heat exchanger, an older unit with repeated failures, or very high bills are the main reasons to replace. See the furnace repair cost guide.