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Common problems, answered › Furnace keeps turning on and off
Grasshopper · the Albany Capital Region, NY

Furnace keeps turning on and off?

Why does my furnace keep shutting off? Here is the honest version: what you can safely check yourself in the next five minutes, what a technician usually finds when it is not that, and exactly what it costs to find out.

By Grasshopper Heating, Cooling, Plumbing & Electrical, the Albany Capital Region, NY. Updated October 12, 2026. Rated 4.9 out of 5 across 2600 reviews.

If this means no heat in the house: A home with no heat is treated as urgent and prioritized, often same-day. The emergency button on the booking page gets a callback within 60 seconds.

Check these first

  1. Replace the filter first. A choked filter is the single most common reason a furnace overheats and shuts itself off early.
  2. Open every supply register and move anything sitting on a return grille. The furnace needs the air to go somewhere.
  3. If the thermostat sits in direct sun or right above a register, it may be satisfied long before the house is.
  4. If it lights, runs a few seconds, and quits, over and over, that is a flame it cannot prove. Stop restarting it and call.

If one of these fixes it, you owe us nothing and we are glad. If not, the next part is what the visit is for.

What a technician usually finds

Short cycling. Rapid cycling is a clogged filter, a mis-set anticipator or a limit set too low, and the commonest of those is the filter. A restriction on the supply or the return is what starves it, and a low amp draw at the motor is the tell.

Limit control. A limit trips because the chamber overheated, and the chamber overheats because the air that should carry the heat away is blocked: a dirty wheel, a dirty coil, a choked filter. Adjusting the limit is not the repair; moving the air is. The blockage came past the filter, so the filter is the fix that keeps it from coming back.

Flame sensor. If cleaning the sensor makes it run, that is not the repair. The board is usually the thing that has gone weak and is no longer sending the sensor enough voltage. And what kills the board is the same unfiltered air that packs the cabinet and rusts everything in it.

These are the causes in the manufacturers' troubleshooting charts and the trade handbooks our technicians train on, in plain words. The visit proves which one it is with a meter before anything is replaced.

What keeps it from coming back

Improper ventilation trips the motor on its overload, and it takes a long time to get there, so it runs hot for months first.

A filter that is changed and a temperature rise that is checked every call is what keeps the limit from ever tripping.

What it costs to find out

$59 on weekdays, $159 evenings and weekends. Published and final, pre-tax, and the price is the price whether we find a loose wire or a bad motor.

Book the $59 visit online Or call 518-545-3271

Real arrival windows, including evenings and weekends. Paying is what confirms the slot; the office calls to confirm the window.

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