Why Is My Furnace Blowing Hot Air?

May 16, 2019

Recently, we ran an article on why your air conditioner might be blowing hot air – basically, the last thing you want an air conditioner to do! We love furnaces as much as we love air conditioners, so we don’t want to give them the cold shoulder, especially because they’ll sometimes give us the cold shoulder! That’s right, just as your air conditioner might blow hot air, your furnace can sometimes blow cold air, pretty much the worst thing on a cold Winnipeg winter’s night. Here are some easy fixes for cold air blowing from your furnace; you can solve these problems yourself!

Check Your Thermostat

This is one of those tech support fixes that you think looks silly until you check your thermostat and realize it is the problem. Basically, if your thermostat is set too low, you’ll end up getting cold air out of the vents – pretty simple! Turn the thermostat up, and check for warm air; if you’re getting it, you’ve solved the problem!

Auto to On

Your furnace might be set to “On” instead of “Auto”. This doesn’t mean “keep the furnace heating my house at all times”; rather, it means “keep the furnace’s fan on at all times”. That means the fan will be running even when your furnace isn’t heating your home, which will just blow cool air around the house. Not only is this producing cold air, it’s running the fan for no reason, which can speed up mechanical breakdown. Swap from on to auto, and the problem may well be solved!

Overheating Furnace

When your furnace overheats, the heat shuts off, but the fan continues to run. This occurs because an overheating furnace is a fire hazard, and the fan cools things off so everyone stays safe. After this, the furnace will shut off entirely, so what’s coming out of your vent will looks like: Hot Air—–>Cold Air—->No Air. More often than not, this occurs because the filter is dirty; this blocks airflow, which means the hot air circulates through your furnace, overheating it. Replace the filter, restart your furnace, and everything should be good to go!

Other Problems

The three fixes above should cover pretty much everything you can fix on your own; past that, you’ll want to call an HVAC pro. They’ll take a look at your system and determine what’s causing you problems, then give you an estimate of how much it’s going to cost to fix it. When looking at that estimate, you should think about how much it costs, how old your furnace is, and how often you’ve needed repairs in the past. In some cases, it will be better to get a furnace installation contractor to replace your furnace entirely; this can save you money on energy bills and on potential future repairs.


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