Having a dirty air filter in your furnace can cause short cycling. While a faulty flame sensor will lead to an immediate shut-off, a dirty filter will allow your furnace to run for several minutes and then shut down. You might notice that the air being pumped out of the heat grates is significantly hotter than normal.
Restricted airflow
Blocked vents or a clogged air filter may cause your furnace to run and then shut off too early. It's easy to fix these issues on your own. You should change your furnace filter at least once every three months. Follow our guide to do it yourself.
There are multiple reasons why your furnace is short cycling. These could include a dirty filter, blocked vent, or malfunctioning flame sensor. You can switch for a clean furnace filter, or have your HVAC technician resolve a more complicated issue.
That's something called short cycling, and you'll want to call an HVAC guy out ASAP. It's possible that it's a faulty thermostat, but also likely it's something serious - the system is leaking refrigerant, the PCB is damaged, etc etc.
This can be caused by a couple of possibilities. It's not that you're blower is out of sync, it is either going bad or if this is an older furnace with a fan-limit switch, it is cooling down the heat exchanger too fast (or the unit is underfired) and the fan switch is turning it off.
The simple solution: Turn your furnace off and check the filter. If it's dirty or it's been 3 months or more since you changed it, put a new, high-quality filter in place.
When the filter becomes clogged, it restricts airflow to the carburetor, potentially resulting in engine stalling. You should inspect your air filter for any signs of dirtiness and replace it annually as most filters require. Another reason why your leaf blower might start and then stall is due to old gas.
Insufficient airflow or insufficient gas pressure. A defective, malfunctioning ignition board, flame sensor, light switch, thermostat, thermocouple, fan limiter, or draft inducer fan. The drainage line is blocked, resulting in a full condensate pan. Temperatures are so low that the furnace cannot stay lit.
Short cycling is a common sign of a bad flame sensor. The sensor thinks that there isn't a flame, so it shuts off the gas as a safety mechanism. Except, there is a flame and without the gas to supply it, it dies. This is a frustrating problem, but an HVAC technician can fix it.
Blockages in the Flue Pipe
Once the gas starts to build up, this may cause your heater to overheat and turn off early. If your furnace keeps shutting off after a couple of minutes, it may be necessary to work with a licensed professional to remove the blockages in your flue pipe and HVAC system.
If your furnace keeps turning off, check for issues such as: Dirty Air Filters. A clogged filter restricts airflow, causing the furnace to overheat. Replace air filters every 60 to 90 days to prevent this problem.
The most common problems that cause a furnace to short cycle include: An overheating heat exchanger. A dirty flame sensor rod. A blocked flue pipe.
When a furnace is short cycling, it's working hard to produce heat but isn't making any, causing strain on your furnace. If left unchecked, this could cause major issues for your furnace resulting in hefty repairs.
There is a work-around to waiting. If there is no safety risk (like a gas leak), a furnace can be reset to bypass this wait. Turn off the furnace's power switch and wait 10 seconds before turning it back on.
If it's broken or malfunctioning, it may fail to detect the flame and shut off the gas supply as a precaution, even if the burners are actually lit. This can result in your furnace starting the ignition process but failing to stay lit.
Most likely, your furnace is making a clicking noise and not providing heat because your furnace's spark igniter is trying to ignite your pilot light or burners but is failing to do so. In other words, there's an ignition system malfunction that needs to be fixed. Otherwise, your furnace won't start.
A furnace cycling on and off repeatedly can be caused by various reasons, from dirty filters and obstructions in ducts and registers to incorrect thermostat settings and faulty limit switches.
Restricted carburetor – Old or bad fuel can leave a gummy residue inside the carburetor creating a restriction. This will prevent the proper ratio of fuel and air from entering the cylinder which can cause the engine to stall after running for a few minutes.