Furnace Not Heating? What to Check Before You Call in Colorado Springs

Before the checklist, watch one start attempt. Set the thermostat a few degrees above the room temperature and listen. What the furnace does next is the diagnosis in miniature: nothing at all, a click and a hum but no flame, burners that light and die within seconds, or a blower pushing air that never warms up. Write down which one you got, because a technician will ask, and the answer shortens the visit. Then work through the checks in order. Each one takes minutes, costs nothing, and between them they close out a good share of no-heat calls without a single tool.

• Thermostat: set it to Heat, a few degrees above the room temperature, with the fan on Auto rather than On. A dim, blank, or resetting screen usually means dead batteries, which stop more furnaces than any broken part.
• Filter: slide it out and hold it up to a light. If light cannot pass through it, change it and give the furnace a few minutes to retry. A filter clogged solid overheats the furnace and trips its limit switch, which looks exactly like a breakdown.
• Breaker and furnace switch: check the panel for a tripped breaker, then find the switch by the furnace that looks like a light switch. It gets knocked off by accident all the time, including the ones at attic entries and basement stairs.
• Blower door: the front panel presses a safety switch, and a panel left loose after a filter change stops the furnace dead. Push it firmly shut and listen for a restart.
• Registers and returns: open any supply vents that were closed for the summer and move furniture, rugs, and boxes off the return grilles, so the furnace can move the air it heats.
• Error light: look through the small window on the furnace panel for a blinking light and count the pattern. Do not take the panel off to chase it. The count is what the technician needs, and it is stored in the board even if the furnace later restarts.
• Gas supply: try another gas appliance. If the stove and water heater are also out, the problem is the gas supply, not the furnace. The valve handle beside the furnace should sit parallel to its pipe, which means on. If it sits across the pipe and nobody in the house turned it off, leave it alone and call. Never keep relighting a pilot that will not stay lit.
• Condensate: furnaces with white plastic vent pipes make water as they run. Find the drain hose or the small pump beside the furnace. A pump reservoir full of water, or a drain hose that is kinked or frozen where it crosses an unheated attic or crawlspace, trips a safety switch and stops the furnace. Emptying a pump reservoir is fine. Bypassing its float switch is not.
• Outside intake and exhaust: the two plastic pipes on the side of the house clog with wind-blown snow here, sometimes overnight. Clear snow and ice away gently by hand, and check them again after every storm while the cold lasts.

Attic furnaces and crawlspaces

Plenty of Colorado Springs homes keep the furnace in the attic or in a crawlspace, and the same checks apply, with one change of emphasis. On an attic furnace in a cold snap, suspect the condensate line first: it runs through unheated space, freezes before anything else, and shuts the furnace down on its safety switch. In a crawlspace, work the list in the same order and take a flashlight. If reaching the unit means an icy ladder or a crawl you are not comfortable making, that is a fair stopping point. Skip it and say so when you call.

The altitude fault a homeowner cannot fix

Some no-heat faults only show up in deep cold here. At about 6,035 feet, a furnace proves its vent is clear with a pressure switch that reads air pressure, and thin air gives that switch less to read. A furnace that was never derated for altitude, at 4 percent for each 1,000 feet above 2,000 feet, can light happily on mild days and lock out when it has to run hard. No homeowner adjustment exists for that, and guessing helps nobody. If yours starts, runs briefly, and quits only on the coldest nights, note the pattern and tell the technician, because that exact pattern is a known fault on our furnace repair page.

If the furnace will be out for more than a few hours, work this list while the house still holds its heat. At the 7 degree design temperature, an unheated house can fall below freezing inside in about a day, and faster on windy nights or in homes with plumbing on outside walls. Every step below is about buying time on that clock and limiting the damage if a pipe does freeze.

• Drip the faucets: run a slow stream, about the width of a pencil lead, at faucets fed by outside walls. Moving water resists freezing, and the open tap relieves pressure if a section does ice up, which is what actually bursts pipes.
• Open cabinet doors: under every sink on an outside wall, so warm room air reaches the pipes inside.
• Pick one warm room: close the doors to unused rooms, hang a blanket over a hallway opening if you need to, and keep everyone, pets included, in the room you are heating.
• Use a space heater by the rules: flat on the floor, three feet clear of bedding, curtains, and furniture, plugged straight into a wall outlet and never into an extension cord or power strip. Choose one with tip-over and overheat shutoffs, and never leave it running in an empty room or while you sleep.
• A fireplace helps if it is sound: open the flue first, burn only proper firewood, and close the damper again once the fire is fully out.
• Hold the heat you have: close curtains and blinds, keep exterior doors shut, and put a rolled towel along the gap under the front door.
• Find the main water shutoff now: it is usually in the basement, the crawlspace, or the meter box. If a pipe bursts, that valve is the difference between a mop and a flood.

Your water heater deserves one line here. While it runs, it keeps its own tank hot, so the tank itself rarely freezes. The exposed part is the piping that feeds it across a cold garage or crawlspace, and that piping gets the same treatment as the rest: drip the nearest faucet and let warm air reach it. If the wait stretches into days and the house will sit empty and unheated in deep cold, dripping is no longer enough. The safe endgame is to shut the water off at the main and drain the lines, or have a plumber do it, rather than gamble the whole plumbing system on a repair slot.

When you call, describe what the furnace does in your own words, plus anything the checks turned up: the error light pattern, the dead filter, the snow you cleared off the pipes. That detail shapes what the technician loads and tests first. The diagnostic visit is $89, confirmed before anyone is dispatched. On the visit, the technician runs the start sequence step by step, tests the parts your symptoms point to, checks gas pressure and combustion, and confirms the altitude settings. You then get the fault in plain words and a written itemized quote before any part is fitted. The invoice is in your hand before you pay, and there are no tip screens. The full picture of the service, including the local price table, is on our furnace repair page.

Most common repairs land between $100 and $900 for parts and labor. A flame sensor clean or replacement is often $100 to $300, a hot surface igniter $150 to $350, and blower motors and control boards sit at the high end. If your repair lands outside that range, the quote will show why, line by line, before you agree to anything.

Sometimes the honest answer is that the furnace should not be repaired at all: a cracked heat exchanger, or a major part gone on a furnace deep into its second decade. Run the $5,000 rule before you decide, multiplying the age of the furnace by the repair cost, and if the result passes $5,000, replacement usually deserves a hard look. Our furnace replacement cost guide sets out the local replacement prices beside the repair maths. And if a crack is the diagnosis, whoever you use, ask for camera proof of your own heat exchanger and the carbon monoxide reading in writing before you sign anything.

This guide is the homeowner half of a no-heat call. The other half is a technician with the right parts on the truck and the testing gear to prove the fault before replacing anything. When the checks run out, book the visit through our furnace repair service, and when the season turns and the same system will not cool, the rest of the team is on our page for AC repair in Colorado Springs. When the house is warm again, more homeowner guides cover the decisions that come next, from choosing a heating system to what this altitude does to all of them.