What you may be noticing
- The house temperature is falling and registers blow nothing, or only room-temperature air.
- The furnace is completely silent on a call for heat.
- You hear the furnace start, run briefly, then go quiet without producing heat.
- A blinking LED code is visible through the furnace viewport.
- The thermostat display is blank, frozen, or showing an unfamiliar message.
Common causes, in the order they usually turn up
| Cause | Telltale sign |
|---|---|
| Thermostat batteries or settings | Blank display, or set to COOL/OFF, or setpoint below room temperature |
| Furnace switch off or breaker tripped | Furnace completely dead, no lights inside the viewport |
| Blown low-voltage fuse on the control board | Thermostat blank on a hardwired thermostat; furnace unresponsive |
| Clogged air filter | Furnace heats briefly then shuts off, or airflow is very weak |
| Cracked hot surface ignitor | Inducer runs, then everything stops without burners lighting |
| Dirty flame sensor | Burners light for a few seconds, then shut off — often three times, then lockout |
| Blocked vent or intake | Inducer runs but the sequence never advances; common after heavy snow |
| Clogged condensate drain | Water around the furnace base, pressure switch fault code |
| Failed blower motor or capacitor | Furnace gets hot, no air moves, unit shuts down on limit |
| Control board or gas valve failure | Erratic behavior or no response despite good inputs |
Safe checks any homeowner can do
- 1
Set the thermostat to HEAT
Confirm the mode, then raise the setpoint at least five degrees above the current room temperature and wait a few minutes.
- 2
Replace thermostat batteries
Even a dim display is worth fresh batteries. It is the cheapest possible fix and it happens often.
- 3
Check the furnace switch
Look for a light-switch-style toggle on or near the furnace, often at the top of the basement stairs. It gets bumped more than you would think.
- 4
Check the breaker
Find the furnace circuit in the panel. If tripped, switch it fully off and back on once. If it trips again, stop and call.
- 5
Look at the filter
Pull it out. If light will not pass through it, replace it with the correct size before restarting.
- 6
Clear the outdoor vent pipes
On high-efficiency furnaces, make sure the PVC intake and exhaust on the exterior wall are not covered by snow or ice.
- 7
Note the error code
Watch the LED behind the furnace viewport and count the flash pattern. The legend is usually printed inside the door panel.
- 8
Stop and call
If heat has not returned, further troubleshooting belongs with someone who can safely test gas and electrical components.
Where safe checks end
Never bypass a safety switch, open or adjust a gas valve, disassemble burners or the heat exchanger, jump control board terminals, or work on live wiring. If the safe checks below do not restore heat, stop and call 716-412-2677.
No heat right now? Call 716-412-2677 for 24/7 service availability.
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Why this matters more here
During a Buffalo cold snap, an unheated house loses temperature steadily, and older homes across the West Side, South Buffalo, and Black Rock lose it faster. Below-freezing outdoor temperatures put plumbing in exterior walls, unheated crawl spaces, and attached garages at risk. A no-heat call that could wait until morning in October is genuinely urgent in January.
There is also a pattern worth knowing: no-heat failures cluster during the first hard cold snap of the season and during extended lake-effect events. That is when marginal ignitors, weak capacitors, and oxidized flame sensors finally give out, because the furnace is cycling far more than usual.