Furnace won't stay running (short cycling)

A dirty air filter is the most common cause of short-cycling. If your air filter is clogged with dirt, it won’t allow proper air flow to the heat exchanger. That can cause the furnace to overheat and forces the high limit switch to ride to the rescue by shutting the furnace off.

Why does my furnace only run for a few seconds?

A common reason a furnace short cycles is because the heat exchanger, the part that heats your air, is getting too hot due to a lack of airflow. Once the heat exchanger overheats, it trips the high limit switch, which shuts the furnace down to protect it.

What might be the problem if the furnace runs but with short cycles?

A short cycling furnace can cause your home heating system to break down prematurely, which can be a big problem during the winter months. If your furnace is short cycling and you can’t seem to get the problem under control, contact the heating contractors at a professional furnace repair service today.

What does it mean when a furnace is short cycling?

Furnace short cycling refers to the switching on and off of your furnace system without reaching the set temperature on the thermostat. And for those experiencing short cycling, you may notice suddenly that your home isn’t as warm as it should, leaving you and your loved ones cold and uncomfortable.

What causes short cycling on a gas furnace?

What Causes Short Cycling? Furnaces have built-in safety systems that prevent dangerous situations like fires, carbon monoxide leaks, or gas leaks. The most likely cause of short cycling is the fan limiter, which prevents fires and furnace damage by shutting the system down if the heat exchanger becomes too hot.

How do you fix a short cycle on a furnace?

Can a bad thermostat cause short cycling?

Your thermostat could also cause the HVAC system to cycle on and off rapidly, a process known as short cycling. Your furnace or central air conditioner spends a good amount of energy simply turning on and off, which is why you want yours to run for at least 15 minutes at a time before shutting off.

Can a bad flame sensor cause short cycling?

Bad Flame Sensor

Flame sensors are also subject to corrosion. This is because your furnace produces small amounts of water during the heating cycle. Over time, this can lead to corrosion and rust in your furnace, resulting in short cycling.

Is short cycling an emergency?

Sure, short-cycling is a warning of a problem–like a refrigerant leak. But the real problem is what short-cycling does to your cooling system. It shortens the system’s service life, increases repair needs, causes and increase in energy use and a decline in home comfort.

Why does my furnace turn on every 10 minutes?

Bad Thermostat: If your thermostat has a problem, it can cause your furnace to run cycles that are either too long or too short. If the thermostat is sensing the incorrect temperature and not sending a cut-off signal soon enough, or if the battery is dying, your thermostat can cause your furnace to run erratically.

How do you fix short cycling?

How To Stop and Prevent Short-Cycling

Check your air filter. Believe it or not, a clogged air filter can cause a wide variety of air conditioning issues. …
Check your thermostat placement. …
Check your air conditioner’s refrigerant levels. …
Replace the low-pressure control switch. …
Check the compressor.

Why does my furnace keep cycling on and off?

If your furnace keeps shutting off, it could be due to low airflow. There are several indirect issues that cause low airflow. Dirty Air Filters. If you don’t change your air filters often enough, the filters will become dirty and clogged, which means the heat exchanger retains heat and eventually causes it to overheat.

How do you know a thermostat is bad?

7 Ways to Tell Your Thermostat Is Broken

Thermostat Has No Power. …
AC or Furnace Won’t Turn On. …
Heater or AC Won’t Turn Off. …
Thermostat Doesn’t Match Room Temperature. …
Thermostat Doesn’t Respond. …
Short Cycling. …
Thermostat Forgets Programmed Settings.

How do you test a furnace thermostat?

How to Test Your Furnace Thermostat

Step 1: Reset the thermostat lower or higher. …
Step 2: Make sure the thermostat is ON. …
Step 3: Check the wiring. …
Step 4: Turn breaker back on. …
Step 5: Reexamine wires. …
Step 6: Wrap wires together.

How do you tell if you need a new thermostat in your house?

Signs You Need a New Thermostat

Heating or cooling system will not turn off or on.
The temperature reading is incorrect.
Recent spike in your energy bill.
Frequent temperature fluctuations.
Thermostat is 10 years old or older.

Do furnace thermostats go bad?

Thermostats don’t typically have a set lifespan for maintenance, repair, or replacement (unlike air conditioners that need a tune-up every year). Still, you can generally expect your thermostat to last at least 10 years. After a decade, thermostats may start malfunctioning.

Can low batteries affect thermostat?

Having a low battery can cause all kinds of bad readings on the thermostat, which means the thermostat may kick on when it’s not supposed to, the room temperature may be incorrect, and the central system may not work at all.

How much is a new thermostat?

Thermostat Replacement Cost

The average cost to replace a thermostat in a home is $140 to $350, including the unit and professional installation. Thermostat prices range from $15 to $250, depending on the type, brand, and features. Nest thermostat installation costs $100 to $200 for labor if the unit is provided.

Can I change my thermostat myself?

Can I do it myself? An experienced DIY-er can install most programmable thermostats and some smart thermostats. Don’t forget to turn off the breaker to the HVAC equipment!

Can I replace my thermostat myself?

It is possible to save some money by installing or replacing your thermostat yourself, but you will need: Basic electrical knowledge. A general understanding of the type of equipment being used.

Furnace won’t stay running (short cycling)