- 3880 S. Jason St. Englewood, Co 80110
- 720-333-1011
When temperatures drop in Colorado, the last thing you want is a furnace that suddenly blows cold air. It’s one of the most searched heating issues in Englewood, Lakewood, and Centennial—and one of the most frustrating for homeowners. The good news: most causes are fixable, and not all of them require a full repair or replacement.
If you’ve turned on your heat and you’re greeted with a blast of cold air instead of warmth, here are the most common reasons why it happens, the signs to watch for, and what you should do next.
Before jumping to worst-case scenarios, check how long the system has been running. When a furnace first starts a heating cycle, it may blow room-temperature or slightly cool air for a short period. This is normal.
If warm air doesn’t appear after a few minutes, or the cold air continues throughout the cycle, you’re dealing with something more serious.
Thermostat settings are one of the most overlooked causes of cold-air issues. Two settings matter here:
On: The blower runs constantly, even when the furnace isn’t producing heat.
Auto: The blower only runs during a heating cycle.
If your thermostat is set to “On,” the blower may circulate cold air between heating cycles. Switching to “Auto” is often an easy fix.
Make sure:
The temperature is set above room temperature
The system is set to “Heat”
A mis-set thermostat can mimic furnace failure.
A clogged air filter restricts airflow, forcing your furnace to work harder and overheat. When that happens, the furnace activates a safety switch that shuts down the burners—leaving the blower to push cold air.
A dirty filter can cause:
Weak airflow
Cold or lukewarm air
Short cycling
Higher utility bills
Replacing the filter often restores normal heat quickly.
Gas furnaces rely on a flame sensor to confirm there is an active flame. If that sensor gets coated with dust or soot, it can’t detect the flame correctly. As a safety measure, the system shuts off the burners—but the blower may continue running, pushing cold air.
This issue becomes more common as furnaces age.
Signs include:
Furnace turns on, then off within seconds
Repeated short cycles
Cold air blowing from vents
A technician can clean or replace the flame sensor to restore regular operation.
An overheating furnace will shut off the burners to protect the system, causing cold air to blow. Overheating is almost always caused by airflow issues, including:
Blocked vents
Closed registers
Dirty filter
Blower motor problems
Internal mechanical failure
Because overheating can lead to serious damage, it’s important not to keep running the system.
If your furnace uses a pilot light and it goes out, or if your electronic ignitor fails, the burners will not ignite—resulting in cold air from your vents.
This often happens due to:
Dirty pilot assembly
Faulty ignitor
Gas supply issues
Thermocouple failure
If the system repeatedly fails to ignite, a professional inspection is recommended.
Your furnace needs consistent gas flow to produce heat. If the supply is disrupted or partially restricted, the system may run but never warm up.
Possible causes:
Gas valve malfunction
Low gas pressure
Utility supply issues
Recently shut-off gas line
Never attempt to adjust gas components yourself. If you smell gas, turn off the system and call for service immediately.
Your furnace needs consistent gas flow to produce heat. If the supply is disrupted or partially restricted, the system may run but never warm up.
Possible causes:
Gas valve malfunction
Low gas pressure
Utility supply issues
Recently shut-off gas line
Never attempt to adjust gas components yourself. If you smell gas, turn off the system and call for service immediately.
Sometimes the furnace is producing heat—but it’s escaping into your attic, crawlspace, or basement because of leaky or disconnected ductwork. This is common in older homes in Englewood and Lakewood.
Signs include:
Hot furnace but cold rooms
Uneven heating
Dusty air
Higher utility bills
Repairing ductwork can dramatically improve comfort and efficiency.
If your furnace is 15–20 years old, blowing cold air can be an early sign of system failure.
Age-related issues include:
Weak or failing blower motors
Cracked heat exchangers
Repeated ignition failure
Major component wear
At this stage, continued repairs may cost more than replacing the unit. Many homeowners move to a high-efficiency Daikin furnace for better heat, lower bills, and long-term reliability.
You should call for furnace service if:
Cold air persists after checking the thermostat
The furnace is short cycling
You smell gas
The furnace won’t ignite
There is little to no airflow
The furnace is old and unreliable
Cold-air issues can be simple—but they can also signal major safety failures. A licensed technician can pinpoint the real cause and prevent costly damage.
As a family-owned heating company serving Englewood, Lakewood, and Centennial since the 1960s, we approach every home the same way:
1. Diagnose the issue accurately
We look beyond symptoms to find root causes.
2. Fix it first if repair is possible
If we can safely repair your furnace, we will—without pushing unnecessary replacements.
3. Show you clear pricing and options
No surprises. No pressure.
4. Install Daikin when replacement is the right choice
Industry-leading efficiency, reliability, and comfort.
Your heat should work—without stress, confusion, or upselling.
If your furnace is blowing cold air and you live in Englewood, Lakewood, or Centennial, schedule a diagnostic today. One of our certified heating technicians will identify the issue, explain your options clearly, and get your home warm again as quickly as possible.
Warm homes. Honest service. Since the 1960s. That’s Elevation.
Too hot? Too cold? Middle of the night?
Call Elevation Heating & Air—anytime, day or night. We’re always ready to keep you comfortable.
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