Unit turns on and off

“My unit will turn on and off repeatedly, what could be causing this?”

When your unit is turning on and off repeatedly you could have a problem in the unit itself. What I have also seen is that the unit is too big for the house.

I was in a conversation with someone the other day and they said, “ I have a 3 ton unit, how about I go to a 5 ton unit, won’t that cool the house faster?” Yes, it will cool the house faster but the challenge is you are not dehumidifying. It is coming on, cooling the house down, then turning right back off. The most power the unit pulls is when it first starts up. We did some energy training in Raleigh a few years ago and the tests showed that if your unit ran for 8 hours constantly, it pulled less power than if it was started and stopped 3 times.

Starting and stopping is not good for the power of the unit, it is also not good for the unit itself, it is kind of like miles per gallon with your car. Obviously it is more efficient for you to hop on the interstate and drive 8 hours than it is for you to spend 8 hours in stop and go traffic. You get better gas mileage on the long trip. Your unit is the same way, so if it is cutting on and off, chances are your unit is too big for the home or there is a problem that is happening, either way, you need to have it checked by a professional. It is satisfying the thermostat very quickly then turning it right back off. It is getting cold or warm again then it is coming back on, satisfying it then turning it right back off. The challenge with that is wear and tear on the unit as well as running up your electric bill. It is wasting electricity and when it gets to the summer time you are not dehumidifying the house properly.

You walk into some of the houses where yeah it is 75 degrees but it feels clammy and sticky, that is because it is not dehumidifying correctly. When it is 30 degrees outside or 90 degrees outside for that unit to run all day is not uncommon. It is not going to hurt anything, it is better for it to run longer than for it to start and stop a lot. I would have it checked out to make sure it does not have any problems in the unit itself, but if the unit is okay then you have to look at the home and the duct system as well.

We tell our guys all the time, there are three aspects to a home. The unit, the home, and the duct air distribution system. Is something causing this to happen? Did I change something? Did I change the window? Did I leave something open? Are we missing insulation? Is something causing this to happen? Check all those things to make sure it is operating correctly, if all of those check out then we need to do a load analysis on the house to make sure the unit is sized for the house properly.

Your friend in comfort and energy savings,

Derek Cole

Derek Cole is the General Manager of One Hour Heating & Air Conditioning®, an independently owned and operated franchise based in Laurinburg, North Carolina since 1953. He has more than 14 years of experience in the HVAC industry and has created two You Tube broadcasts, The Comfort Experts and #AskDerekCole, filled with tips and tricks on saving energy and being comfortable. He was named the Top 40 under 40 in the HVAC industry by the News magazine and featured in Entrepreneur Magazine Franchise Player Spotlight. Derek has also been seen on CBS, FOX, NBC, ABC, and Bloomberg Business sharing about One Hour Heating & Air Conditioning®.

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