Common Reasons For Furnace Breakdowns

If you are having issues with your gas furnace or electric heat pump, there’s a good chance it’s listed below –– from how to solve it, to immediate steps you can take to remedy the situation and what you should expect to pay.

Are you thinking about investing in a new furnace or heat pump? Home Advisor has a great guide to help you choose what’s right for you. While a furnace may have more safety concerns, a heat pump issue is more costly to fix. 

Cost Key:

$ – DIY
$$ – low $100’s
$$$ – high $100’s to low $1,000
$$$$ – many $1,000’s/full replacement

Gas Furnace Problems 


Many natural gas furnaces are in it for the long haul. They can operate efficiently for up to 20 years. In Southern California, where winter months are not severe, purchasing the most expensive furnace may not be necessary.

The biggest issue with natural gas furnaces? It has always been, and will be, safety hazards. Along with being combustible, natural gas leaks can leave your home susceptible to carbon monoxide poisoning. Most homes come equipped with a carbon monoxide detector. If you don’t have one, you GET one!  They cost just over a $20 on Amazon. However, if a furnace is installed correctly, it should also have a backup protection system, preventing harmful elements from entering your home.

My Gas Furnace Won’t Kick On

One of the biggest reasons for a furnace breakdown may not even take a trip to the basement to fix – your thermostat. Often times, homeowners make meaningless service calls only to later discover their heating function wasn’t switched on, or an older thermostat unit ran out of batteries. The same can be said about your power grid. Make sure your breaker isn’t tripped off. Other problems to look for:

  • Gas supply. If there is a disruption to your gas supply, your furnace will not work.
  • Pilot light. If you can not re-light it, you may have an issue with the sensor or assembly.
  • Your furnace has an ON/OFF switch. Locate it to ensure its in the ON position.
  • Condensate pan. If the condensate pan is full, your furnace will not run.
  • If the blower motor isn’t working, you will need a replacement part.
  • Make sure the ventilation pipe on the side of your home or your roof is clear of debris/ice.

Looking for help? Check out our DIY Widget on our maintenance page! Don’t forget to get a tune-up every year — especially if your gas furnace is an older model. 

Cost to Repair Furnace: $-$$

If your furnace is not turning on, thermostat and breaker issues can be DIY fixes. Turn your furnace to 5-10 degrees higher than your normal room temperature. 

Repairing a pilot light sensor or thermocouple might require a service call, but it’s not a major repair. A blower motor carries a similar quote, though a full replacement might cost hundreds of dollars.

For more information, check out this video —————->

My Furnace Is Not Blowing Hot Air

Again, the thermostat is your first order of recourse. If your furnace is set to ON instead of AUTO, it may be running the fan in its normal cycle. 

A common cause is a dirty air filter. Don’t forget to change your air filters regularly – especially if you live with a family and/or pets. A dirty air filter will block air flow and cause the furnace to overheat.

A furnace overheating too often can ruin your heat exchanger, which can be a major issue.

Cost To Repair Furnace Not Blowing Hot Air: $-$$$$

In most instances of your furnace not blowing hot air, a thermostat issue or air filter problem is something you can take care of on your own. But a cracked heat exchanger is like a needing a transmission replacement in your vehicle. It is a labor-intensive component that could cost thousands to replace.

My Gas Furnace is Making a Noise

Is it cranking, pounding, grinding, hissing, whining? Whatever it is, ignoring these noises, seemingly harmless as most could be, may cost you. Some common examples

Bang – This can happen when your burners are dirty, and the gas builds up, delaying the ignition until it finally lights. This can be an issue, as small gas explosions like this can crack your heat exchanger.

This sound also happens when your ducts expand. Your duct system may not be sized properly or needs better support, your vents are closed, or you have a dirty air filter.

Grind – This may be an issue with your squirrel cage blower wheel. It could be lose or the mount could be broken.

Whine – This can be a blower belt issue. Your shaft bearings need lubricated, or you have a bad blower motor.

For more information on strange furnace noises, check out this sponsored content from A.J. Perri, a home services provider on the USA Today Network.

Cost to Repair Furnace Making A Noise: $-$$$

A variety of furnace noises can bring about a variety of service costs. Generally, blower wheel/motor fixes or replacements run in the hundreds. If your duct system is an issue, talk to your insurance company, particularly if you inherited the home recently. A new duct system can cost thousands of dollars.

My Gas Furnace Won’t Shut Off

Check your air filter and thermostat. Your furnace may need to continuously run to provide heat because the airflow is blocked, or your thermostat may simply be in the ON position.

Other issues could include a fused contact, or a control board short-circuit.

Cost to Repair Furnace Not Shutting Off: $-$$$

You can purchase control boards online and replace them yourself for about half the cost of a service technician, but you do run the risk of sacrificing quality.

My Gas Furnace Pilot Light Is Out

Furnaces that have them have instructions on how to light the pilot light. Check for a gas supply issue by testing your faucet and stove (if it is gas-powered). If your furnace pilot light works and then keeps burning out, you might have a thermocouple malfunction.

Cost To Repair Pilot Light Out: $-$$

Newer furnaces do not have pilot lights. If a home you recently purchased has a furnace with a pilot light, it could be more than 10 years old and require routine maintenance.

Furthermore, it might be costing you more to run over the course of its lifetime than it would be to install a new furnace. Same Day has financing and rebates available to suit the needs of any homeowner!

My Home Smells Like Gas

Natural gas is actually odorless and tasteless, which is why you should have a carbon monoxide detector in at all times. The smell of mercaptan (rotten eggs) often accompanies this as an additive to help residents detect leakage.

If you smell this, turn off your gas supply and gas-using appliances immediately and extinguish all flames, ventilate the area, and call your gas provider.

Cost To Repair Home Smelling Like Gas: $-$$$$

Gas is typically a publicly owned entity, so the onus is likely on your gas company to fix the issue. However, if you have a leak inside the home, it depends. A leak to an appliance can be a couple hundred, but a mainline can cost thousands.

My Gas Furnace Is Cycling Too Frequently, Repeatedly, or Short-Cycling

Poor thermostat placement can be a common cause of short cycling. If your thermostat is near a heat source, it could mis-read the actual temperature of your home. Another common issue is an oversized furnace that pumps too much heat into a home in an unequal fashion.

Other things to watch for include dirty air filters and rusted flame sensors.

Cost to Repair: $-$$$

Replacing a flame sensor can cost hundreds of dollars, and is not recommended as a DIY fix. Thermostat replacement costs can vary in the low hundreds, but if you are savvy enough to attempt a DIY fix in your house, it might require little to nothing at all.

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