Diagnosing Residential Air Conditioner Problems

Your residential air conditioning system needs periodic attention. Even so, problems can happen. Before calling for help, it’s possible to save time and money by doing some AC troubleshooting of your own.

AC Doesn’t Run

  • If your system doesn’t turn on at all, make sure it’s getting power. Check the fuse or circuit breaker. If your system has a secondary breaker near the outside unit, verify that it’s on.

Air Conditioner Turns On and Off Too Often or Not Often Enough

  • Your system cycles based on a sensor you know as the thermostat. Verify that it is set in the ‘cooling’ position. If it is located in a small, isolated room, other rooms may not cool properly. Consider moving it to a larger, more centrally located room.
  • If your system starts and stops frequently, it may be too big, or a register could be blowing on a thermostat.
  • If your system seldom cycles off, you could have low refrigerant levels or faulty relay switches.
  • Dirty filters and intakes can prevent your system from pulling in enough air to properly cool your home. Check your air filters and exchange them regularly to keep your home comfortable. Alternatively, consider upgrading to a media filter, which only requires semiannual attention.

Water Accumulating Under the AC

  • Pooling water in your AC unit’s drip pan could mean a broken condensation pump or a blocked drain line (if it’s the latter, you can try clearing the line with bleach). Either way, that water means it’s time to schedule service. You should consider installing a safety shutoff switch that will turn the unit off if drain lines back up.

AC Runs, But Doesn’t Blow Cool Air

  • If your system blows warm air, check that the outside unit is running, and that its airflow isn’t blocked by leaves or debris.
  • If the fan on the outside unit isn’t turning, turn the thermostat fan switch to the ‘off’ position. If the inside fan continues running, turn off your system breaker and schedule service. Your problem could be insufficient refrigerant. Your air conditioner is a closed system. If it’s low on refrigerant, you have a leak, which commonly occurs at valves or in the coil. Finding a leak is work for a professional.
  • If your blower motor is running but not cooling, your system is probably frozen, and needs professional attention.

What Causes AC Freeze-Ups?

When ice forms on air conditioning units, it robs them of their ability to cool. These freeze-ups can lead to expensive repairs. That’s why it’s critical to understand the causes of freeze-ups and the steps you can take to prevent them.

Common causes of freeze-ups include:

  • Dirty filters
  • Dirty evaporator coils
  • Low refrigerant levels
  • Closed-off supply registers

As it cools your home, your AC unit condenses water vapor into liquid that drains outside. When airflow is impeded by a dirty air filter or other obstruction, water ends up freezing on the evaporator coils before the condensed water can be drained away. The AC still runs, but doesn’t properly cool, and uses more electricity. Running your AC with ice on the coil can result in serious damage that requires repair or replacement of the compressor, the most expensive component in your system.

Thankfully, there are steps you can take to prevent AC freeze-ups.

If you see ice forming on the outdoor unit or pipes leading from the compressor, check your filters. Blocked or closed vents can also impede airflow, so make sure that yours are open and free of blockages.

Other common causes of freeze-ups include faulty fans that don’t circulate air through your ductwork, faulty thermostats, and low refrigerant levels. Low refrigerant levels make the coils too cold, preventing the system from absorbing enough heat, leading to a freeze-up. Since air conditioners do not burn refrigerant, low levels indicate a leak. Locating a leak is work for a licensed technician, who will likely need to recharge your refrigerant.

Cold weather is another cause of freeze-ups in certain regions. When nighttime temperatures drop below 60 degrees Fahrenheit, you should switch off your AC and open windows, or install an ambient temperature control, which allows air conditioners to operate properly in lower temperatures.

Annual maintenance tune-ups are your best defense against freeze-ups. These checkups should include cleaning both indoor and outdoor coils, checking and replacing air filters, a check of refrigerant levels, and a variety of other important elements of your system.

If your air conditioning system isn’t operating properly, or hasn’t been looked over by a professional recently, it’s time to call the experts at Gilmore. Our trained technicians will take all the steps necessary to ensure that your AC unit doesn’t experience a freeze-up or other breakdown when you need it most during the hot days ahead this summer.