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6 Reasons Your Furnace Keeps Freezing Up

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Did you know your furnace can freeze during the winter? Sometimes, the hot exhaust gases freeze after they condense due to air not flowing properly or drainage issues. The resulting water doesn’t have time to fully exit the venting area before turning to ice. A frozen furnace is only a problem when temperatures drop below 32°F, but that possibility becomes a reality between November and April in Indiana

If you’ve noticed your furnace freezing up, it doesn’t mean it’s broken. It could be a simple issue like a clogged air filter or a mechanical issue that an HVAC professional can fix. Call Dugan Air Heating and Cooling if your furnace freezes, and our experienced technicians will find the cause of the problem and fix it for you fast so your house stays warm. 

Common Causes of Furnace Freezing

If you’ve noticed your HVAC freezing up, look for these common causes:

  • Dirty air filter

A dirty air filter blocks airflow in your furnace. This makes the blower motor have to work harder, which causes condensation to build up on the evaporator coil. At low temperatures, this water freezes.

Changing your furnace’s air filter isn’t difficult as long as you know where to find it and how it fits into the furnace. If you’re unsure, ask an HVAC expert to show you the next time they’re at your home. 

  • Dirty coils

Furnace condenser coils are there to transfer heat energy, and when they’re grimy and covered in dirt, they lose their ability to function efficiently. This prevents airflow in and around the coils, which results in freezing, as they can no longer move heat effectively. 

Scheduling regular maintenance on your HVAC system with Dugan Air helps prevent this issue because our technicians clean the coils as part of their tune-up service. 

  • Blocked vents or collapsed/damaged ducts

A simple and often overlooked cause of a frozen furnace is closed or blocked vents or damaged ducts. When the air from the furnace has nowhere to go, the condensation in the hot air sits stagnant in the vents, which may cause ice to form. 

Luckily, this is a simple fix. Open the vents and keep furniture and other items away from them. If your ducts are collapsed or damaged, you’ll likely need a professional to replace the damaged parts and get your home heating system back up and running.

  • Blower fan problems

When a blower fan has problems, the airflow is affected, which allows condensation to form and freeze inside the furnace. Repairing or replacing your heater’s fan should be done by a professional. Call Dugan Air if you suspect your blower fan has gone out. 

  • Broken thermostat

If the thermostat incorrectly reads the temperature in your home, or if you’ve set it too low during a cold snap, the furnace will have difficulty maintaining an above-freezing temperature in the internal components. This can lead to ice formation wherever condensate forms. 

  •  Drainage problems

The heat exchanger inside the furnace creates moisture that leaves the furnace in a condensate pipe, which goes to a floor drain or outside. A clogged condensate drain, a frozen uninsulated pipe, or any clog in the line leads to freezing when temperatures dip below 32°F. 

What To Do if Your Furnace Is Freezing Up

If your furnace keeps freezing, take the following steps to address the issue:

  • Clear ice from the furnace, condensate drain, and anywhere else it accumulates (you can use hot water or hot air).
  • Clean the condenser coil and change the air filter.
  • Check your thermostat settings to make sure they’re not set too low, as this can make it hard for the furnace’s internal mechanisms to maintain heat.
  • Look around the furnace for any refrigerant leaks or pooling water.
  • Check your furnace and the house to ensure there isn’t anything blocking the airflow in the furnace or the ducts.

If your furnace keeps freezing even after you try all of these DIY steps, or if you’re uncomfortable with getting hands-on with your furnace, call Dugan Air for furnace repair. You may have a mechanical or structural problem that they’ll need to address. 

How To Prevent Furnace Freezing Up

The best way to prevent your furnace from freezing is to schedule regular maintenance with your trusted local HVAC professionals. A trained technician knows where to look for common issues inside your furnace, including the air filters, the coils, and the thermostat. 

Along with scheduling an annual tune-up, you can also do some things yourself (if you feel comfortable). Here are some simple tasks homeowners can do to help the furnace work properly:

  • Change the air filter often, following manufacturer guidelines.
  • Keep vents open and move anything that might block airflow, like furniture/draperies/rugs.
  • Check the condensate drain for blockages and consider adding insulation to prevent ice from forming.
  • Clean dirt off the evaporator coils and the fan.
  • Test your thermostat and make sure its readings match the actual temperature in your house.
  • Install a self-regulating heating cable system on the condensate line for an automatic safeguard against freezing.

If your furnace keeps freezing after trying these tips, contact Dugan Air Heating & Cooling today. Our expert local HVAC technicians can be at your door quickly to diagnose and fix the problem. 

Call Dugan Air Today for All Your HVAC Needs

From emergency furnace repairs to regular HVAC maintenance, Dugan Air Heating & Cooling is Indiana’s top furnace service center. Our expert techs will assess your issue and give realistic, cost-effective, and long-lasting solutions without overcharging or upselling. 

To schedule an appointment, call us or use our online contact form. Our passion for quality service shines through in all we do, with a touch of Irish charm.

Frequently Asked Questions

Is it normal for HVAC to freeze in the summer?

No. If your HVAC has ice on the inside or outside of the unit, there’s a problem. Schedule service with a professional who can find the cause of the problem and fix it. 

Does low refrigerant cause freeze-up?

Yes. Low refrigerant levels can cause freeze-up in your HVAC system because there’s less pressure inside the coils, making them too cold and causing moisture to freeze. Your HVAC system needs adequate refrigerant to absorb heat and work properly. 

How do you keep the furnace drain from freezing?

The simplest way to keep your furnace drain from freezing is to insulate the pipe with an insulated wrap or a weather-proof sleeve. Also, consider shortening the pipe so the water has a shorter distance to travel (and less time to freeze inside). This helps prevent a high-efficiency furnace condensate line from freezing.

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