A heating or cooling system normally runs for a while, reaches the temperature you set, and rests. If yours starts, runs for a few minutes, stops, and starts again over and over, that's called short cycling. It wastes energy, leaves rooms uneven, and wears out parts, because starting is the hardest thing a system does.
Things you can check
- The filter. A clogged filter can make a furnace overheat and shut itself off, then restart when it cools, again and again. Change it first.
- The thermostat's location. If it's in direct sun, near a supply vent, a lamp or a kitchen, it warms or cools faster than the rest of the house and shuts the system off early.
- Thermostat batteries, and whether its settings have been changed.
- The outdoor unit. Is it clear of plants and debris, and is the coil clean?
- Ice on the refrigerant lines or indoor coil, in cooling mode.
Causes that need a technician
- A system too big for the house. It satisfies the thermostat in minutes and shuts off. One of the most common causes, and the reason sizing matters. See what size system you need.
- A dirty flame sensor on a gas furnace, which shuts the burners off seconds after lighting.
- Overheating from restricted airflow, closed or blocked vents, or a failing blower.
- Low refrigerant from a leak, which can trip a safety switch. See signs of a refrigerant leak.
- Electrical problems: a failing capacitor, relay or control board.
When to call
If changing the filter and checking the thermostat doesn't stop it, call. Short cycling rarely fixes itself, and a few weeks of it can shorten a compressor's life. Call us at 805-965-6326 or send us a message.