24/7 Emergency AC & Heating Repair Across MarylandCall now: (855) 459-5498
☎ (855) 459-5498
☎ Call (855) 459-5498 – 24/7
Home › Blog › Why Your Furnace Keeps Turning On and Off (Short Cycling Explained)

Why Your Furnace Keeps Turning On and Off (Short Cycling Explained)

By Bens Air Conditioning  |  Serving all of Maryland

If your furnace fires up, runs for a couple of minutes and shuts off, then repeats, it's short cycling. Left alone, short cycling wears out parts, raises gas bills and eventually leaves you with no heat on the coldest night of the year.

Dirty air filter

Restricted airflow makes the heat exchanger overheat, and the high-limit switch shuts the burners off to protect it. Replace the filter first.

Dirty flame sensor

A flame sensor coated in residue can't confirm the burners lit, so the control board shuts the gas off within seconds. Cleaning it is a quick furnace repair.

Blocked flue or pressure switch problems

Modern furnaces check for proper venting before igniting. A blocked exhaust, a failing inducer motor or a stuck pressure switch causes rapid cycling and error codes.

Thermostat location or wiring

A thermostat near a heat register, in direct sun or with loose wiring can call for heat and cancel it repeatedly.

Oversized furnace

A furnace that's too big for the house satisfies the thermostat in minutes and shuts down. This is common in additions and renovations. A proper heating installation with correct sizing solves it.

Cracked heat exchanger

Overheating and short cycling can be symptoms of a cracked heat exchanger, which is a carbon monoxide safety risk. An annual furnace tune-up includes a heat exchanger inspection.

Short cycling never fixes itself. Call (855) 459-5498 for same-day no-heat and furnace repair anywhere in Maryland.

Need help now?

(855) 459-5498

24/7 AC and heating repair anywhere in Maryland

More from the blog

Services

AC or heat out? We're on call right now.

24/7 emergency air conditioning and heating repair anywhere in Maryland. No overtime fees.

☎ Call (855) 459-5498