Most AC problems show up as one of a few symptoms: the system will not start, it blows warm air, it freezes up, it turns on and off too often, it smells, or some rooms stay warmer than others. Start with the quick checks below, then find your symptom for a full guide.
Quick Checks Before You Call
- Thermostat: Set it to Cool, a few degrees below the room temperature, with the fan on Auto.
- Power: Check for a tripped breaker, and make sure the disconnect switch by the outdoor unit and the switch on the furnace or air handler are on.
- Air filter: Check the air filter every month, and clean or replace it when it is dirty.
- Outdoor unit: Keep plants and debris at least 2 feet back from the unit.
- Condensate drain: A clogged drain line can shut the system off or cause leaks.
Find Your Symptom
| What you notice | Full guide |
|---|---|
| The AC will not turn on | Air conditioner won’t turn on |
| It runs but blows warm air | Why is my AC blowing warm air? |
| Ice on the coil or refrigerant lines | Why is my AC freezing up? |
| It turns on and off too often | Why does my AC keep turning on and off? |
| A smell when it runs | Why does my house smell when the AC runs? |
| Some rooms too hot or too cold | Solving uneven room temperatures |
| Higher bills, weaker cooling | AC coil cleaning |
Common AC Symptoms and When To Call a Professional
Central Air Conditioner problems can present many symptoms. It’s important to be aware of all potential problems, which can include unusual sounds, smells, air temperature changes and visual clues. Here are some common symptoms to keep a look out for:
1. Inadequate Cooling
One of the most obvious signs is that your AC isn’t cooling your space as effectively as it should. This could be due to several issues, including low refrigerant levels, a dirty air filter, or a malfunctioning compressor. See why an AC blows warm air.
2. Poor Air Flow
Are you feeling little or no air coming from all the air registers throughout the home? A clogged air filter, a frozen evaporator coil or a problem with the blower motor are common causes. Are some rooms cooler than others? This usually indicates an air delivery problem caused by an inadequate air duct system or undersized AC unit. See solving uneven room temperatures.
3. Unusual Noises
Today’s central air conditioners are designed to operate quietly. If you start to notice unusual sounds like grinding, squealing, or rattling, it’s time to call Central Heating Cooling Plumbing Electrical to have your AC unit checked.
Some sound is normal. A soft thump or whir when the system starts and stops, and the steady sound of the blower moving air, are part of everyday operation. Grinding, squealing or rattling usually means a part is wearing out, such as a loose belt, a failing bearing or a worn motor. A clogged air filter can also make the blower whine as it struggles to pull air through the system.
4. Unpleasant Odors
Foul or pungent smells coming from your air conditioner can indicate that there is mold in your ductwork or AC unit. The cause could be a clogged drain line under the condensate pan.
5. High Humidity Levels
An AC unit should moderate humidity levels indoors. If it’s not maintaining comfortable humidity levels, that could be a sign of an issue.
6. Frequent Cycling On and Off
Is your AC cycling on and off more frequently than usual? This is known as “short cycling” and can have many causes, including a dirty air filter, dirty or frozen evaporator coil and thermostat issues. Because there can be many underlying causes, it’s best to call a professional AC service to have the problem diagnosed.
7. Leaks or Moisture Around the Unit
If you notice any leaks or moisture around your AC, this could indicate a refrigerant leak, which is a serious issue that needs immediate attention. It could also indicate that the condensate drain is blocked or broken.
Other signs of a refrigerant leak include warm air from the vents, higher humidity indoors, longer run times, ice on the evaporator coil, and a bubbling or hissing sound, sometimes even when the system is off. Refrigerant must be handled by a certified HVAC technician.
8. A Sudden Increase In Your Energy Bill
If your energy bills are higher than usual, but you haven’t been using your AC more often or there haven’t been drastic temperature changes, it could mean your AC is running inefficiently. Dirty coils are one common cause. Scheduling regular preventative AC maintenance can help keep your heating and cooling system operating at peak efficiency, reducing energy consumption.
If you notice any of these AC symptoms, it’s generally a good idea to have a professional HVAC technician inspect your system to accurately diagnose and fix the issue. If your air conditioner is older and keeps needing repairs, replacing it may cost less in the long run than repairing it again.
AC Troubleshooting FAQ
Why is my AC running but not cooling?
Check the thermostat, the air filter and the outdoor unit first. If the air is still warm, see why an AC blows warm air. Low refrigerant, dirty coils and a failing compressor are common causes, and they need a technician.
Should I turn my AC off if it freezes up?
Yes. Switch the thermostat from Cool to Off, and run the fan to thaw the coil. See what to do if your AC is frozen.
When should I call for AC repair?
Call if the quick checks do not fix the problem, or if you notice grinding or squealing, a burning smell, ice that comes back, or water leaking around the unit. Air conditioner repair from Central Heating Cooling Plumbing Electrical covers Kalispell and the Flathead Valley.
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