Common problem · Same day
Furnace blowing cold air?
The most common call we get every Denver winter. Most of the time it’s one of four things, and one of them you can fix yourself in five minutes.
- $99 diagnostic, credited to the repair
- Same-day across Denver
- No overtime fees
How urgent
Same day. Call now if it’s below freezing outside.
- Call if: The flame is yellow or flickering
- Call if: You smell gas or the CO alarm sounds
- Call if: It’s below freezing and the checks above didn’t help
What it usually is
The causes, most common first.
- 1
Thermostat fan set to ON
The blower runs between heating cycles and moves room-temperature air. It feels cold. Switch the fan to AUTO.
Free. Switch the fan to AUTO.
- 2
Clogged filter tripped the limit switch
The furnace overheats, shuts the burners off, and keeps the fan running to cool down.
A new filter and a reset
- 3
Dirty flame sensor
The furnace lights, runs a few seconds, shuts off, tries again. A ten-minute cleaning.
A quick cleaning, first visit
- 4
Failed igniter or gas valve
The furnace never lights at all. Parts are common and usually on the truck.
A common part, usually on the truck
Every fix gets a written price before any work. The $99 diagnostic is credited toward it.
Try this first
What to check before you call.
If one of these fixes it, great. If not, you’ve saved us five minutes on the diagnosis.
- 1
Set the thermostat fan to AUTO and the mode to HEAT, 5° above room temperature.
- 2
Pull the filter. If you can’t see light through it, replace it.
- 3
Turn the furnace power switch off for 30 seconds, then on.
- 4
Look at the flame through the sight glass: steady blue is good; yellow or flickering means stop and call.
Who we are
Hello. We’re Duality.
Duality Heating and Air LLC is a Denver heating and cooling company run by one licensed technician and the people he trusts. We fix furnaces, ACs, heat pumps, and the air in your home, and we do it the way we’d want it done at our own house. Comfort, in perfect balance.
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Denver-based
One technician who lives here, not a call center in another state.
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Price in writing
You approve the number before we touch a tool. It never changes.
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Fix before replace
We repair what can be repaired and show you both numbers when it can’t.
Questions
Furnace Blowing Cold Air, answered.
Is a furnace blowing cold air dangerous?
Usually not, but a yellow flame or a cracked heat exchanger can be. If the flame isn’t steady blue, shut it off and call.
How much does this repair cost in Denver?
The $99 diagnostic finds it, and you get a written, flat-rate price before any work. Most of these are finished on the first visit with parts from the truck.
From Denver neighbors
- HVAC service
Cecilia Gomez
Google review“Professional, knowledgeable, and incredibly helpful. He took the time to explain everything clearly, answered all of my questions, and made the entire process easy and stress-free. I truly appreciated his honesty, responsiveness, and attention to detail.”
- AC repair
Jessica Russman
Google review“Very honest and reliable. He showed up on time and fixed our old AC after we had several companies try to sell us a new one. We would 1000% recommend Duality to anyone who wants to feel confident they’re dealing with the right company.”
Same-day help
Furnace blowing cold air? Tell us. We’ll call back in minutes.
Three quick taps. A real Denver dispatcher calls to confirm your address and get a truck moving. No call center, no waiting on hold.
- Written flat-rate price before any work starts
- Same-day service across the Denver metro
- No overtime fees, nights and weekends included
Prefer to talk? (720) 447-0177, open 24 hours.
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