Why Is My Furnace Blowing Cold Air? A Pittsburgh Tech Answers

Turned on the heat recently but feel cold air coming from your vents? We feel for you!

What’s causing this? There are a number of issues that could be causing your furnace to blow cold air, including:

  • Your thermostat is set to “ON”
  • Your filter is dirty
  • Your ducts are leaking

Below we’ve outlined these issues and the steps you or a professional can take to resolve them.

If you’ve exhausted all DIY efforts, you’ll need a professional to diagnose and/or repair your furnace. Just contact us and we’ll send out a furnace repair tech right away.

3 possible reasons your furnace is blowing cold air:

1. The Thermostat is set to “ON”

We know it sounds obvious, but it does happen! If your furnace is blowing hot air one minute and cold air the next, this is likely your issue. When the fan is set to ON, your furnace’s blower is circulating air 24/7, regardless of whether the air that it’s circulating is heated or not.

The solution: Switch your fan setting to AUTO instead of ON. This will ensure that the blower is only running when the air is heated, eliminating the cold-air problem that you’re currently experiencing.

2. Your filter is dirty

A dirty filter can be a huge problem for your furnace. A clogged air filter can sometimes confuse homeowners into thinking their furnace is blowing cold air when, in reality, the real problem is that there’s not enough hot air blowing to warm the room or house.

When the filter is dirty, it restricts the amount of air that the furnace can heat up and blow into the room. If the dirty filter isn’t replaced with a clean one, it will eventually cause the furnace to overheat and shut off completely.

The solution: Check and clean your filter if needed.

  1. Turn off power to your furnace.
  2. Locate your furnace filter. If you’re not sure where it’s located, contact us. We can help you find it over the phone or send over a tech to replace the filter for you.
  3. Determine how dirty it is…if you can see through the filter, this likely isn’t your cold-air problem. If you can’t, it’s time to clean your filter!
An example of a clean filter (left) and a dirty filter (right).
  1. Find a replacement filter that’s the same size. Bringing your old filter to the store with you is a great way to ensure you get the right size filter.
  2. Replace the old filter with a new, clean one.

Another tip would be to unblock and open any supply vents, the metal grates where the heated air comes out. There could be trapped debris here that is affecting your airflow.

3. Ducts are leaking

Not only are duct leaks a major energy suck, but they can be a massive heat suck too. If there is major damage to your air ducts, those ducts could be sucking in cold air and blowing that cold air into your home.

The solution: Unfortunately, if this is your problem, you probably need to enlist a professional.

Still getting cold air? Our Pittsburgh techs can help.

If you’ve tried everything on this list and are still experiencing cold air, it’s time to contact a professional in furnace repair in Pittsburgh. We’re available 24/7 and can fix your furnace in as little as 45 minutes.