On a hot afternoon, it's natural to wonder whether an air conditioner that hardly stops is wearing itself out or running up the bill. The short answer: running for long stretches on a hot day is normal, and it's what the system is built to do. Running all day on a mild day is a different story.
Long runs are normal in a heat wave
An air conditioner is sized to keep up on the hottest days of a normal summer, not to cool the house down in minutes. When it's well over 90 degrees outside, it may run almost nonstop in the afternoon and still only just hold the temperature you set. That's not harmful. In fact, long steady runs are easier on the equipment than turning on and off every few minutes, and they take more moisture out of the air.
When nonstop running points to a problem
If it runs and runs on a mild day, or never quite reaches the temperature you set, something may be wrong:
- A dirty filter or coil cuts the airflow, so the system takes longer to do the same work.
- Low refrigerant means a leak somewhere, and the system can't move heat as it should.
- Leaky ducts in an attic or crawlspace can lose cooled air before it reaches the rooms.
- A system that's too small for the house, or for an addition that was added later, can't keep up. See what size system you need.
- An aging system slowly loses capacity.
Other signs to watch for alongside long run times: ice on the lines, warm air from the vents, or a cooling bill much higher than last summer's.
Keeping the cost down
- Pick a temperature and leave it. On a very hot day, raising the set point a few degrees while you're out is better than turning it off and asking it to cool a hot house from scratch.
- Cool down before the expensive hours. If your electric plan charges more in the late afternoon and evening, cool the house a little earlier and let it coast.
- Set the fan to Auto, not On, so it isn't blowing air across a warm coil between cycles.
- Keep the sun out. Close blinds on west- and south-facing windows in the afternoon.
- Change the filter and keep the outdoor unit clear of plants and debris.
- Have it tuned up once a year. A clean coil and the right refrigerant charge make a real difference. Our maintenance plan reminds you when it's due.
When to call
If your system runs all day on mild days, can't reach the temperature you set, or is icing up, call us at 805-965-6326 or send us a message. Our NATE-certified technicians will find out why before recommending anything.
Related
- Air conditioning repair and installation
- What size system do I need?
- What happens at a maintenance visit
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