If your house too hot or too cool, your problem could be the thermostat. Troubleshooting thermostat problems isn’t that difficult. Once you find out what the problem is, you can fix it or decide you need to hire a professional. Look for the following problems:
It’s in a bad location. The thermostat shouldn’t be located over a lamp, over a TV, or near any heat source. Drafts will read as lower temperatures and send wrong commands to the air conditioner or furnace.
It needs cleaning. When older mechanical thermostats malfunction, those with lever-set temperatures and contact switches usually need cleaning only. To clean your thermostat, remove the cover and dust inside with a soft brush. To clean contacts, slip a piece of paper between them, moving the paper very lightly back and forth.
Its anticipator needs adjustment. If your air conditioner or furnace cycles on and off too seldom or too frequently and you have a mechanical control, try adjusting the anticipator — usually a flat metal pointer on a scale. If heat starts and stops too often, move the anticipator a smidge higher. If it starts and stops too seldom, adjust it a tad lower. Wait a few hours to see if the adjustment was enough.
You need new batteries. Electronic thermostats with digital readouts and keypads rarely fail. Just put in new batteries when the low-power light comes on.
With simple maintenance and light cleaning, thermostats, whether electronic or mechanical, will function best and as they should — for comfort.