HVAC Services
Emergency Furnace Repair in Thornton, CO
We repair no-heat, cold-air, and short-cycling furnaces across Thornton and north Denver, diagnosing the actual failed part before quoting anything, so a cold house on a Front Range night gets an answer tonight instead of a guess. Call 720-687-3822.
Cold Air From the Vents Has a Findable Cause
When the heat quits on a January night, you need three things: what broke, how fast it can be fixed, and the price before anyone opens a toolbox. Our technicians work to NATE-certified standards, inspect the system on site, and name the part and the number before the repair starts.
We answer after-hours and weekend calls for furnace repair in
Thornton,
Broomfield, Northglenn, Brighton, Commerce City, Denver, Federal Heights, and Erie. Locally owned and operated since 2012, with offices in Thornton, Denver, and Brighton, and free estimates on replacement.
Common Furnace Problems We Fix, and What Causes Them
The Furnace Runs but Blows Cold Air
Heat that never arrives usually traces to ignition or flame sensing. A dirty flame sensor, a cracked or failed hot surface igniter, or a furnace locking out on a safety switch will run the blower without ever firing the burners. We test the ignition sequence and the sensor's microamp signal to see which stage is dropping out.
The Furnace Will Not Turn On at All
No response at the thermostat points to power, controls, or a safety circuit. We check the furnace service switch and breaker, thermostat wiring and staging, the control board, the door switch, and the pressure switch and condensate float on a high-efficiency unit.
The Blower Runs Constantly and Will Not Shut Off
A blower that never stops is usually a stuck fan relay, a failing control board, a limit switch tripping on high temperature, or a thermostat wired or set to continuous fan. Restricted airflow from a loaded filter causes the same overheat pattern.
Banging, Rattling, or Burning Smells
Delayed ignition makes a distinct boom on startup and needs burner and gas pressure attention. Rattling and squealing point to the inducer or blower motor, its bearings, or a loose panel. A burning smell that lingers past the first heating cycle of the season should be inspected rather than waited out.
A Blinking Light on the Furnace
The LED behind the furnace door is an error code, not a warning light. The blink pattern maps to a specific fault, commonly ignition lockout, a pressure switch fault, an open limit, or a flame sensed with no call for heat. Count the flashes and tell us the pattern when you call, and read the legend printed inside the access panel.
Heating Bills Climbing Without a Cold Snap
A furnace using more gas for the same comfort is working against something: restricted airflow, a burner or heat exchanger needing cleaning, duct leakage, or a system short cycling its way through the day. We measure temperature rise and static pressure rather than estimating.
Why Does My Furnace Turn On and Off Every Few Minutes?
Short cycling means the furnace reaches a shutdown condition before the house reaches temperature. It is one of the most misread symptoms we see, because nothing sounds broken. Four causes account for most of it:
- A clogged air filter or closed and blocked registers starve the blower, the plenum overheats, and the high limit switch shuts the burners down early.
- A dirty flame sensor stops proving flame a minute or two into the cycle, so the control board drops the gas valve and retries.
- A blocked flue or intake, or a failing pressure switch or inducer motor, opens the safety circuit mid-cycle.
- A furnace oversized for the house heats the air near the thermostat fast, satisfies the call, and restarts minutes later.
Sizing is the one cause a repair cannot solve, and it is worth knowing which you have before spending money. We separate them by watching the full ignition and shutdown sequence with the gauges on the system.
When to Call, and What You Can Safely Check First
Call for furnace repair when:
- Your furnace is blowing cold air instead of heat
- Your system will not start or keeps shutting off
- You notice unusual smells, including a gas odor
- Your home is not reaching the temperature you set
- Your system is making loud or unfamiliar noises
Before you call, a few checks are safe and occasionally solve it. Confirm the thermostat is set to heat with the setpoint above room temperature and fresh batteries in it. Look at the air filter and replace it if light will not pass through. Check that the furnace service switch on or near the unit is on and the breaker has not tripped. Confirm the gas shutoff valve at the furnace is in the open position. On a high-efficiency furnace, check the condensate drain and pan for standing water, since a backed-up drain trips the float switch and stops the system.
Annual furnace maintenance is what keeps a weak igniter or a fouled flame sensor from becoming a no-heat call in January. Most of the parts we replace at midnight in a cold house show up as a reading on a fall tune-up.
Safety First: What to Do If You Smell Gas
A strong gas odor near the furnace is a call to your gas provider first, from outside the house, before you call anyone else. Take these steps in order:
- Leave the home immediately and take everyone with you.
- Do not use light switches, appliances, or your phone inside the house.
- Do not relight a pilot or reset the furnace.
- Call your gas provider or 911 from outside, at a safe distance.
- Once the provider clears the home, schedule a professional inspection.
We inspect and repair the gas train, burners, heat exchanger, and venting once the home is safe. A carbon monoxide alarm sounding is the same sequence: everyone outside, then emergency services, then service.
What Does Furnace Repair Cost in Colorado?
You get the diagnosis and the price before any work begins, and the exact number comes after we have the panels off. These are the ranges homeowners in our area typically land in:
- Diagnostic service call: $99 to $175, applied toward the repair if you move forward.
- Flame sensor cleaning or replacement: $150 to $300.
- Hot surface igniter: $200 to $400.
- Pressure switch or limit switch: $250 to $500.
- Draft inducer motor: $500 to $900.
- Blower motor: $600 to $1,400, higher for a variable-speed ECM motor.
- Control board: $500 to $1,000.
Where a repair is a large fraction of a replacement, we show you the math both ways instead of steering you. Financing through Wells Fargo Home Projectsis available, subject to approved credit.
When Replacement Is the Honest Answer
A cracked heat exchanger is the one finding that ends the conversation. It is a combustion safety problem, not an efficiency problem, and it is not something to patch. We show you what we found before we say it.
Age and repair history matter after that. A furnace past 15 to 20 years facing a second major component failure, or one with a failed heat exchanger, is usually money better spent on
furnace installationthan on the next part. A high-efficiency replacement also opens up
utility rebates and tax credits through Xcel Energy, Power Ahead Colorado, and United Power that often take a meaningful amount off the project.
Ready to Get Your Heat Back On?
You don’t have to wait and hope the problem resolves itself. With the right diagnosis and repair, your furnace can be restored quickly and safely.
What to Expect From Start to Finish
When you schedule furnace repair with VO Heating & Cooling, the process is clear and focused on getting your system working again as quickly as possible. You’ll get direct communication, straightforward recommendations, and work completed using NATE-certified standards.
01
Call and Scheduling
You’ll speak with a local team member to set up service as soon as possible.
02
System Diagnosis
Your furnace is inspected to identify the exact cause of the issue.
03
Clear Repair Options
You receive straightforward recommendations and pricing before any work begins.
04
Repair and Testing
The repair is completed and tested to ensure safe and reliable operation.
280 Google Reviews, 5-Star Average
Homeowners across Thornton and north Denver have left us a 5-star average across 280 Google reviews. You can also see the furnaces, air conditioners, and ductless systems we have installed in these neighborhoods on our recent projects page.
Furnace Repair Questions Homeowners Ask Us
Who do I call for emergency furnace repair in Thornton, CO?
VO Heating and Cooling handles emergency and after-hours furnace repair across Thornton and the north Denver metro at 720-687-3822. We are locally owned and operated with offices in Thornton, Denver, and Brighton, so a no-heat call is answered by a technician close by rather than routed to a queue.
Why is my furnace blowing cold air instead of heat?
The blower is running but the burners are not staying lit. The usual causes are a dirty flame sensor, a failed hot surface igniter, a furnace locked out on a safety switch, or a thermostat set to fan rather than heat. Testing the ignition sequence identifies which one within the first part of a service visit.
Why does my furnace turn on and off every few minutes?
Short cycling happens when the furnace hits a shutdown condition before the house reaches temperature. A clogged filter overheating the high limit, a flame sensor failing to prove flame, a blocked flue or pressure switch fault, or a furnace oversized for the home are the common causes. Only one of those, sizing, cannot be fixed with a repair.
How much does a furnace repair cost in Colorado?
Most furnace repairs in our area fall between $150 and $900 depending on the part, with a diagnostic service call running $99 to $175 and applied toward the work if you proceed. Blower motors and control boards run higher. You see the price before the repair starts, every time.
Can you do furnace repair near me in Broomfield today?
We serve Broomfield daily and schedule same-day furnace repair whenever the day's route allows, including after hours during a cold snap. Call 720-687-3822 and we will tell you honestly when a technician can be at your door.
What does a flashing light on my furnace mean?
The blinking LED behind the furnace door is a diagnostic error code, and the number of flashes points to a specific fault such as ignition lockout, a pressure switch failure, or an open high limit. A legend is printed inside the access panel. Counting the pattern before you call speeds up the diagnosis.
Is my furnace dangerous if it smells like gas?
Treat any strong gas odor as a safety issue. Leave the home without touching switches or your phone, then call your gas provider or 911 from outside. Once the home is cleared, the system needs a professional inspection of the gas train, burners, heat exchanger, and venting before it runs again.
Where We Handle Furnace Repair
Furnace Repair in Thornton, CO
Our main shop sits on Hudson Court in Thornton, which is why Thornton no-heat calls are usually the shortest drive of our day. We work on the mid-1990s and 2000s builds across Original Thornton and the newer neighborhoods north of 136th, and we carry the igniters, flame sensors, and pressure switches those furnaces fail on.
Furnace Repair in Broomfield, CO
Broomfield homes run everything from 80% single-stage furnaces to high-efficiency condensing units with condensate pumps and PVC venting, and the drain-related lockouts on the latter are a regular winter call for us. We service both, along with the ductless and dual-fuel setups common in newer Broomfield construction.
We also handle furnace repair in Northglenn, Brighton, Commerce City, Denver, Federal Heights, and Erie, plus the surrounding Adams, Jefferson, and Boulder county communities.
Heat Restored by a Local Crew You Can Reach
Our NATE-certified technicians hold Master Mechanical credentials and Trane Comfort Specialist status, and owner Jason Van Orden has more than 20 years in the trade. We have been repairing furnaces for Thornton and north Denver homeowners since 2012, with free estimates on replacement and the price in front of you before the work starts.
