Check these five things before you call
Roughly a third of the no-start calls that come in from Arvada end without a repair. The furnace was fine; something upstream of it was off. Run this list first. It takes ten minutes and costs nothing.
- Thermostat. Set to Heat, not Cool or Off, and set at least five degrees above the room temperature. If the screen is blank, change the batteries. A dead thermostat is the single most common reason a furnace "won't turn on."
- Power. Look for a light switch on or beside the furnace that looks like it belongs in a hallway. That is the furnace power switch, and it gets bumped. Then check the breaker panel for a tripped breaker labeled Furnace or Air Handler.
- Filter. Pull the filter. If you cannot see light through it, replace it. A packed filter overheats the furnace, the high-limit switch trips, and the unit refuses to start until it cools down.
- Door panel. The blower compartment door has a safety switch. If the panel is not seated flush, the furnace will not run. Push it in until it clicks.
- Gas supply. The gas valve handle on the pipe feeding the furnace should run parallel to the pipe. Perpendicular means off. If other gas appliances in the house are also dead, call Xcel, not us.
If you smell gas or rotten eggs, stop here. Do not flip switches or relight anything. Leave the house, then call Xcel Energy at 800-895-2999 or 911 from outside. A furnace call can wait; a gas leak cannot.
What it usually is when those five are fine
If the thermostat is calling and the power is on but nothing happens, or the furnace starts its sequence and quits, the cause is inside the cabinet. In order of how often they show up on Arvada trucks:
Failed ignitor
The hot surface ignitor glows to light the burners. They are brittle, they age, and they fail most often in the first cold snap of the year when the furnace goes from idle to running ten times a day. You will hear the inducer fan start, a pause where the click or glow should be, then a shutdown. Three tries and the board locks out.
Dirty flame sensor
The burners light for three to five seconds, then drop out. Repeat, repeat, lockout. A thin rod next to the burners is coated in oxidation and cannot prove to the board that there is a flame. Cleaning it is a fifteen-minute job. Replacing it is not much more.
Pressure switch or blocked vent
The inducer motor runs but the burners never try to light. The pressure switch is not proving draft, which is either a failed switch, a cracked hose, or a vent blocked by snow, ice, or a bird's nest. On a high-efficiency furnace the PVC vent out the side of the house is the first place to look after a storm.
Control board
Dead silence with power confirmed at the switch, or a status LED blinking a code you can read off the panel door. Boards are the pricier common repair, and on a furnace past fifteen years they open the repair-or-replace conversation.
Blower motor or capacitor
The burners light, the heat exchanger warms, the blower never comes on, and the furnace shuts itself down on the high limit. A humming sound with no fan is the capacitor. Silence is more often the motor.
What the repair costs in Arvada this quarter
Prices verified September 2026| Repair | What you will notice | Parts and labor |
|---|---|---|
| Diagnostic visitCredited toward the repair | Tech confirms the fault and quotes in writing | $49 - $180 |
| Hot surface ignitor | Inducer runs, no glow, lockout | $150 - $300 |
| Flame sensor, clean or replace | Lights, drops out in seconds | $150 - $300 |
| Pressure switch | Inducer runs, burners never try | $150 - $400 |
| Capacitor | Humming, blower will not spin | $120 - $300 |
| Blower motor | Heat with no airflow, shutdown | $450 - $1,600 |
| Control board | Dead or blinking a fault code | $500 - $1,200 |
| Compiled from published Denver-area contractor pricing and national cost guides, Q3 2026. Updated quarterly. The written price comes before any work starts, and the diagnostic is credited when you go ahead. Full list on the furnace repair cost page. | ||
What to have ready when you call
Three things shorten the call and sharpen the range: the brand and rough age off the sticker inside the front panel, what the furnace does when the thermostat calls (nothing, clicks, runs then quits), and whether you have any heat at all right now. If you send a photo of that sticker through the photo quote, the tech can often name the likely part before the truck leaves.
Arvada, Olde Town, Applewood, Wheat Ridge, Leyden, Candelas: the trucks run all of it, and no-heat calls go to the front of the board. On most days that means the same afternoon.