Why Is There Ice on My Air Conditioner?

Even on a hot summer day, ice can form on your air conditioner. One common symptom of a frozen AC is lukewarm air coming from the supply registers. If you notice this problem, learn why there’s ice on your air conditioner and what to do about it.

Reasons Ice Is Forming on Your AC Unit

Several issues could be causing this problem. Here are the most likely culprits:

  • A low refrigerant level can make the evaporator coil too cold, causing ice to form. Leaky refrigerant lines or an undercharged system could be to blame.
  • A dirty air filter could result in low airflow to the evaporator coil. An insufficient flow of hot air over the coil could allow it to freeze.
  • Closed supply registers could reduce airflow through the system so dramatically that the air conditioner freezes up. Make sure you keep at least 80% of your home’s supply registers open to prevent ice on the air conditioner.
  • An insufficient fan speed could be another reason for poor airflow and a frozen evaporator coil.
  • Thermostat problems may keep the air conditioner running all night, even when it’s cold outside. The relatively low outdoor temperature could reduce hot airflow over the evaporator coil enough that ice forms.
  • Drainage problems can prevent condensation from dripping off the evaporator coil and draining away. If something blocks the condensate drain, the backed-up water can freeze on the evaporator coil. Then, the ice blocks the drain and makes the problem even worse.
  • An improperly tilted window air conditioner fails to drain properly. When condensate sticks around inside the unit, it can freeze.

How to Handle Ice on Your Air Conditioner

  • Shut off the AC to prevent risking damage to the compressor.
  • While you wait for the ice to melt, locate the condensate drain and make sure it isn’t blocked.
  • If necessary, open up the ductwork and suction out water with a wet-dry shop vac.
  • Use a blow dryer on the evaporator coil or set the thermostat fan to “on” without running the air conditioner to speed up the melting process.
  • For a window air conditioner, tilt the unit outward slightly so melting ice drips outside. This is the proper operating position for window AC units to prevent ice buildup in the future.
  • Once the ice melts and the condensate drain is clear, turn the air conditioner back on. If a frozen evaporator coil was the only problem, the unit should start cooling off your home immediately.

How to Prevent Ice on an Air Conditioner

  • Have the refrigerant level checked.
  • Change the air filter once a month.
  • Keep your supply registers open.
  • Have a technician increase the fan speed.
  • Have a technician check the thermostat for problems.
  • Inspect the condensate drain weekly for blockages.
  • Make sure any window units you have are tilted correctly.
  • Schedule AC maintenance with Rick’s Heating & Cooling once a year.

Call Rick’s Heating & Cooling for Air Conditioner Maintenance & Repair

To learn more about preventing ice on your air conditioner, or to schedule a visit from an experienced cooling technician, please contact us today. We have over 30 years of experience serving Cincinnati and the surrounding areas.

Why Is My AC Filter Turning Black?

Your air conitioner filter is necessary to prevent dust and debris from settling on and possibly damaging delicate HVAC components. If you purchase a higher-efficiency filter, it also removes tiny airborne particles to clean your indoor air.

As your AC filter traps pollutants, it starts to become clogged. This blocks airflow, reducing system efficiency and possibly causing overheating or other issues. Plan to replace your air conditioner filter every one to three months or according to the manufacturer’s recommendations to avoid these problems.

Things That Cause an AC Filter to Turn Black

When you replace your AC filter, you may notice it isn’t just clogged—it has turned completely black! Under normal conditions, the filter should collect grey-colored dust and debris. If the filter is black, here are the possible causes.

Candle Soot

Black soot is a byproduct of burning candles, especially scented candles. If this is the reason your AC filter is turning black, you may also notice soot stains on the walls, carpet, and furniture.

The best way to prevent candle soot from turning your AC filter black is to stop burning scented candles altogether. But if you love your candles and want to continue enjoying their scent, follow these helpful tips:

  • Choose candles that feel hard to the touch at room temperature, a sure sign of fewer impurities and therefore less soot.
  • Trim the wick to one-quarter inch before lighting the candle each time.
  • Avoid buying candles with petroleum jelly or vegetable oil mixed into the wax.
  • Keep airflow around the candle to a minimum to reduce soot production.

Gas Water Heater Soot

Anything powered by natural gas—including your furnace, gas fireplace, and water heater—can produce soot if it operates improperly. Since you’re unlikely to run the furnace or fireplace in the summer, the water heater is the most likely appliance to cause a black AC filter.

Check the color of the water heater’s flames to see if it’s burning cleanly. You want to see a blue flame, which indicates a clean burn and no soot. A yellow or flickering flame could mean you have a problem. To reduce the soot coming from your gas water heater, call a technician to clean the burners and remove any debris blocking oxygen flow.


When you run your AC unit, condensation collects on the evaporator coil. This moisture can transfer to the filter where black, sooty mold can begin to grow. Replace the filter as frequently as once a month to prevent this.

Schedule Air Conditioner Services in Cincinnati

If you’re concerned about the condition of your air conditioner air filter, give Rick’s Heating & Cooling a call. We’ll assess the problem and possibly recommend a different type of filter to better meet your home’s air filtration needs. We can also tell you about our indoor air quality products that can help clean up your air even more, including air purifiers and whole-house humidifiers.

To work with a company that has over 30 years of experience serving Cincinnati and the surrounding areas in southwestern Ohio, contact Rick’s Heating & Cooling today. We deliver all the HVAC services you need to stay cool and comfortable this summer.

Best Thermostat Setting for Spring

Spring is the time of year when you transition from home heating to cooling. As you shift your focus to keeping your home cool, learn the best thermostat setting for spring along with other techniques to stay comfortable and save money.

How to Set Your Thermostat in Spring

On warm spring days, set the thermostat as high as comfortably possible. We recommend keeping your home at 78 degrees F when you’re at home or sleeping. Then, raise the temperature to 85 degrees when you’re gone all day to avoid air conditioning a vacant house.

Continue reading “Best Thermostat Setting for Spring” »

Air Conditioner Repair: Is It an Emergency?

When your air conditioning suddenly burns out or stops working, we definitely consider it an AC emergency for homeowners here in greater Cincinnati. That’s because our high mid-summer temperatures (which often continue through the night) can be dangerous for local families. If this happens to you, Rick’s Heating & Cooling provides emergency AC repair—around the clock—to quickly restore your home comfort.

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What to Consider Before Replacing Your Air Conditioner

Most Cincinnati homeowners will go through an AC repair-or-replace dilemma at some point in their lives, and we’re here with some expert advice to help you decide if it makes more economic sense to keep repairing your old AC system—or replace it with a new, modern and energy efficient cooling system. The decision is not always cut and dried, and personal concerns come into play of course, but here we’ll share some guidelines that will make your choice easier.

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