How to Troubleshoot a Central Air Conditioner

During the summer months we all want our central air conditioners to be working properly and providing lots of cool air. Unfortunately, as with all things both mechanical and electrical--that isn’t always the case--and when we call for cool air--we get nothing. If your central air conditioner is acting up--here are some troubleshooting tips you might try before calling in an air conditioner professional (and paying for a service call).

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Batteries
• Circuit breakers or fuses
• Owner’s manual

1. Start by checking your thermostat. Modern electronic thermostats have a 2- or 3-degree window around the temperature at which they will turn the unit on. Your system may be operating just fine, but the room temperature is still within the window, so the thermostat isn’t calling for cold air. You can check the thermostat’s operation easily, by changing the temperature and seeing if your air conditioner does turn on.

2. Change the batteries in your thermostat. Most electric thermostats operate on battery power, and weak batteries may be affecting your thermostat’s operation. Even thermostats that have low-battery indicators don’t tell you when your batteries are getting weaker. It’s simple and inexpensive to change out the old batteries for new ones.

3. Check your circuit breakers or fuses. Most central air conditioners are on their own circuit, so check the panel to be sure a fuse hasn’t blown or a breaker popped. Breakers or fuses that control your furnace fan may also be part of your air conditioner's distribution system; make sure they are all working properly as well.

4. Look on the outside of your air conditioner itself for reset switches. Many modern units have these and you need to make sure they are set in the working position.

5. If all else fails, find your owner’s manual and see if the manufacturer provided any troubleshooting tips that you haven't tried.

Tips & Warnings

• If your air conditioner was working OK last summer, it's probably a minor problem that’s preventing it from working this year. For example, often in the spring or the first time folks turn on their air conditioner they forget they switched off the breaker last fall.
• There is some good news even if your air conditioner has "given up the ghost." A new modern unit will be much more energy efficient and should save you hundreds of dollars in operating costs every year.
• If you are uncomfortable or unsure of what to do with circuit breakers or fuses, don’t touch them. Have someone who understands how they work or a trained air conditioner professional check your system.

[mobilemama]

on 8/19/2009 My centrqal a/c will not turn off. I have to turn it off at the breaker. I have already replaced the thermostat.

[hault-denger]

on 8/5/2009 As johnatl mentions, check your filter. If your filter is dirty, it will cause you no end of trouble. Replace it. It's cheaper than replacing your A/C unit!

[BCPASSIONS]

on 8/4/2009 Thanks for the great tips! Much needed in Arizona.

[haileyerickson]

on 8/4/2009 Thanks for the tips!

[chrisanimelo444]

on 8/4/2009 Very good article! Very informative. 5*