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Your First Steps in Thermostat Troubleshooting

Posted by Gregg on Aug 25, 2016 9:06:34 AM

wi-fi_thermostat.jpgHave you ever gone to change your thermostat setting and it just doesn’t seem to respond? That can be a nightmare when you are looking for cooling on a humid day or some heat on a frigid one! Maybe it seems to run, but you can’t feel any cool or warm air coming from the vents. Maybe it doesn’t even turn on. Here are some of the first things to check if you need to do some thermostat troubleshooting.

Is There Power?

Since your thermostat is the switch that lets your AC and furnace know when it’s time to turn off and on based on the temperature you prefer, it really needs power to do its job and communicate with all those components and sensors in order to run properly.

So, if it’s a digital thermostat, look for power on the screen. If it is still lit normally then you have power. Otherwise, you aren’t getting juice to your thermostat. Keith Hill, technical support manager at Minnesota Air, says that means you lost power at either the furnace or if it’s a battery powered thermostat, the batteries may be weak. If you are in doubt, change them out.  

He also urges homeowners to see if there is a built-in time delay on the thermostat or AC unit. A time delay is there to stop short-cycling and protect your AC unit from going off and on all day. You may need to wait up to 5 minutes for it to go on. 

“Is the furnace blower running? If so it may not be the thermostat, it may be trouble with the AC  check power to the outdoor unit,” says Keith.

Lastly, when it comes to no power, check to make sure you aren’t part of an energy saver program. That’s where you would have signed up with the power company to allow them permission to switch your AC off during peak periods in exchange for a discount on your energy use.

Is There An Issue With The Settings?

“If the screen looks normal, double check that the unit is set correctly to cool mode,” reminds Keith.  “Many a service call has been made for a thermostat in the ‘Off’ mode.”

And don’t be the person who has it set to heat when you want cooling or cooling when you want heat. Check your settings before you make the call and it can save you some money.

Check The Placement Of The Thermostat/Sensor

If you can see that your HVAC system is running but it’s not reaching your desired temperature – there could be a heat source affecting the thermostat calibration. And according to the Department of Energy, the location of your thermostat can affect its performance. This means it can be affected if there is a lamp placed too close to it, there is direct sunlight hitting it, or a draft from a door or window.

If it’s undercooling in the summer, Keith says it may be the AC unit, not the thermostat.

“Is it running continuously but not maintaining temperature? That’s more likely to be an AC problem. If it runs but shuts off too soon, that could be a thermostat calibration issue. Some thermostats can be easily adjusted by a pro, some are better just to replace,” he says.  

Mechanical thermostats – or ones with no digital screen – can collect dust that can prevent the devices that move inside from doing their job. You can vacuum around the outside of the thermostat to clear any dust or lint, suggests Keith. He says that most mechanical thermostats aren’t very accurate when it comes to number settings, so set it to a known comfort spot on the dial or upgrade to a newer model.

Know When to Call A Pro

Finally, if you do all the troubleshooting steps above  have checked each setting, made sure there is power, etc. – then it’s time to call in a professional. It could be a bad thermostat or an issue with equipment.

“They have the tools and skills to determine the problem,” says Keith. “A pro will be able to verify within a few minutes which it is.”

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