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Trouble shooting thermostat problems

digital thermostat panel

For many homeowners, their entire knowledge and interaction with their central air conditioner begins and ends with the thermostat display panel. So when there's a problem with the thermostat or with the display, they are immediately put at a severe disadvantage in diagnosing problems.

If there's something wrong with your thermostat and you don't know where to start looking for the problem, follow this quick guide. If you still don't feel confident, don't hesitate to call the professionals at John C. Flood.

Check the batteries

One of the easiest problems to diagnose is if your panel display has run out of, or has run low on, batteries. Since most displays have a low battery indicator, it's unlikely that this problem will sneak up on you. Just to be safe, it's best to change your batteries every year whether there's a low battery indicator on or not. Each display panel will be a little different depending on the manufacturer, so it would be best to check your users' manual on specific instructions for you panel on how to change your batteries and what type of batteries you'll need.


If your AC consistently stays on even when your house is much cooler than you have the thermostat set to, you may first want to look at where the thermostat itself is located. Thermostats are generally put in locations like hallways near the middle of the house to ensure they're away from things that could influence the temperature reading. If there are heat producing appliances like TVs, computers or stereos around, their heat emissions could deceive it into thinking your house is much hotter than it actually is. The same effect is achieved by sunlight hitting the thermostat for several hours a day.

The fix, which is a bit more complicated, would be to relocate the thermostat. After unscrewing the panel from the wall carefully disconnect all the wire connections. When you find the new home for the panel you'll have to drill a hole in the bottom of that wall leading to the basement and then thread the wires through that hole to reconnect your thermostat with the furnace.


If dirt and dust get into your thermostat, it's just as likely to throw off the temperature reading as sunlight or appliances. The electrical contacts inside the the panel are especially susceptible to this problems. To fix this, you need to unscrew the panel and use a soft brush or cloth to carefully clean off the wiring. Be very careful not to bend or damage anything and use a screwdriver to tighten any loose connections.

If your cool air isn't coming up when you want it, make a quick a check that everything on your panel is set up correctly. Take a moment to ensure that the display is set to "cool" and not to "heat". You should also check your main electrical panel and make sure the breaker for the furnace and AC is set to "on." If everything is set correctly turn your thermostat all the way down, and if the furnace fan doesn't start, you'll need to call the professionals.

John C. Flood is the Washington D.C., Woodbridge, Virginia and Silver Spring, Maryland AC repair experts and our local technicians will respond to your call and have your system back up and running as soon as possible.