Skip navigation


Carney All Seasons Blog

What You Need to Know About Furnace Short Cycling

If you’ve ever noticed your furnace turning itself on and off every couple of minutes, don’t ignore it. That behavior is called “short cycling,” and it’s a serious threat to the health of your system. If you don’t have the short cycling taken care of as quickly as possible, you are running the risk of your furnace breaking down very soon. Let’s take a look at what causes short cycling, and what can happen if you don’t get it repaired.

The Cause

Short cycling is the result of an interaction between the furnace and a safety part called the “limit switch.” When heat becomes trapped in the furnace, usually because of a clogged air filter, the temperature inside the system will rise to dangerous levels. The limit switch then activates, and shuts down the furnace to prevent it from becoming damaged. The limit switch cannot solve the cause of the problem, though, and when the furnace restarts it will simply overheat again. So, the furnace starts and stops indefinitely, as it continues to overheat and be shut down. If this behavior is prolonged, certain problems will start to develop.


The startup cycle is the most stressful part of the furnace’s operation. It also happens to be the part that the furnace repeats over and over while short cycling. This puts the entire system under more stress than it was designed to handle. Eventually, all of that added stress will lead to parts of the system breaking down. If you don’t act quickly, the entire system may end up dying on you. So, as soon as you notice this happening, you should turn your furnace off and call for repairs.

If your furnace needs repairs, call Carney Plumbing Heating & Cooling. We offer furnace repair services throughout Blue Bell, PA.

Comments are closed.