AC Troubleshooting Guide – How To Diagnose And Fix AC Problems

How To Fix Common AC (HVAC) Problems?


Is your home air conditioning system not working? When struggling with your AC, sometimes the first instinct is to pick up the phone and contact your local HVAC technician. However, certain AC issues are a lot easier to solve than imagined. Learn how to diagnose AC problems today!

Air-Rite Heating & Cooling cares about your time and money. That’s why we’re providing you with a basic air conditioning troubleshooting guide that details common AC problems and the solutions needed to get your home back to its comfort. Never settle for hefty HVAC bills that only need a simple fix—Air-Rite Heating & Cooling has you covered.

Please note that if these solutions don’t solve your air conditioning problems, contact Air-Rite Heating & Cooling right away! Troubleshooting your air conditioning unit may seem complicated, but it’s actually quite simple. Take a look at our air conditioning troubleshooting guide.

1. Check Your Thermostat Settings

The first thing you should always check when experiencing air conditioning problems is your thermostat. From basic models to the most sophisticated programmable versions, these devices can be set to automatically change temperatures throughout the day for higher efficiency and better comfort. Here is how to know if your thermostat might be broken:

  • Inconsistent airflow: Lukewarm air blows from the registers at times while cold air blows at other times
  • Higher than an expected temperature reading on the thermostat
  • No air blowing from the registers


Here’s what to check when examining the thermostat setting:

  • Although a given, check the temperature setting to ensure that somebody else hasn’t changed it to a higher setting.
  • Is your thermostat set for heating instead of cooling the air? If this is the case, simply re-adjust the thermostat to cool, or change the setting to auto so it will automatically change between cooling and heating as temperatures change.
  • Is your fan set on “auto”, “on”, or “off”? If the setting is “on”, the fan will run constantly, even when the system isn’t cooling the air. This may result in warmer air blowing from the registers when the AC unit isn’t operating. Change the fan setting to “auto”; This will resolve the issue by turning off the blower when the system is not actively cooling. If it’s set to “off”, simply select “on” or “auto”.
  • If you have a programmable thermostat, check your “comfort schedule” for any issues, and make sure your programmed settings smatch the times and temperatures you expect when you are home, away, and asleep.

If you make these adjustments and your AC is still not working, contact Air-Rite Heating & Cooling and we’ll provide you with a solution right away.

2. Change Your Dirty Air Filters

That’s right, dirty filters are one of the most common reasons your AC may not work to the best ability. If you’re having AC problems, check for dirty air filters. Most air conditioning systems include an indoor air handler unit. This is usually a furnace or fan coil.

Air filters keep your air running smoothly by trapping dust, dirt, debris, and other airborne contaminants. That’s why filter maintenance is critical to keep your air conditioning unit in pristine condition. When filters are not cleaned or replaced, this will clog your filter and hinder proper airflow.

Common symptoms of Air Conditioning Not Working include:

  • Warmer-than-usual air temperature
  • Weak airflow from your cooling registers
  • AC runs for short periods of time before shutting down and restarting (also known as short cycling)


Before checking your air filter, be sure the thermostat is set for cooling and that the temperature setting is correct. If it’s set correctly and the air is still not working, check your air filter manual to determine how to remove, clean, and/or replace your air filter. Typically, most filters are situated in the furnace cabinet or outside the furnace between the cabinet and the return air duct. If you’ve cleaned or replaced the filter, and your air conditioning unit is still not working, contact Air-Rite Heating & Cooling for immediate assistance.

Check Out Common HVAC Issues And How To Fix Them:

3. Low Refrigerant Level

The refrigerant in your air conditioner system helps to cool your home. This is done when the refrigerant pulls heat from your home and deposits it outside, leaving the indoor air cooler, less humid, and more comfortable. If your refrigerant levels are low, you may experience the following symptoms:

  • The house not staying cool enough
  • System running continuously or for longer than normal cycles
  • AC turning on, then off quickly, several times in a row (also known as short cycling)


With refrigerant, do not attempt to troubleshoot the issue yourself. If your thermostat settings are correct and the air filter is clean, you may be experiencing a leak or other issues related to the refrigerant. If you suspect low refrigerant levels, contact your local HVAC technician for help.

4. Frozen Evaporator Coil

If you have a split-system central air conditioner, the evaporator is a part of the air handler unit that’s typically situated in the home or garage. However, if the indoor unit is a furnace, the coil is located where the outgoing air flows. If it’s a fan coil, the evaporator coil is situated inside the fan coil cabinet. Common signs of a frozen evaporator coil include the following:

  • Little to no cooling
  • Unusually high utility bills
  • Excessive condensate drainage near your indoor unit
  • Frost or ice forms on copper refrigerant lines that come from your evaporator coil cabinet
  • Frost forms on exterior refrigerant tubing or the outdoor unit


Frozen evaporators can be the result of a lot of issues, usually pertaining to an excessive buildup of dust, dirt, and other pollutants on the evaporator coil, air filter, or outdoor condensing unit. Sometimes, it may be due to low refrigerant levels. Whatever the case may be, evaporator coils are not an easily accessible device, and therefore, must be handled by a professional technician. Never attempt to troubleshoot a frozen evaporator coil yourself.

5. Faulty Or Broken Condensing Unit

Typically condensing units sit outside of the home and include the condenser fan, the compressor, and its electronic controls. If you have a broken or faulty condensing unit, you may experience the following:

  • The condensing unit won’t turn on
  • Also known as short cycling, the unit may turn off and on swiftly
  • Little to no cooling coming from the unit
  • The unit runs continuously for long periods of time


If you’re experiencing a faulty condensing unit, you may have an excessively dirty coil or refrigerant leakage. Other potential causes could be shrubbery interfering with the unit: make sure that all shrubbery and plants are at least 1 foot away from the unit to keep clear. Other condensing units issues include a faulty run capacitor, a failing condenser fan motor, or a faulty compressor. If this is the case, you will need to contact an HVAC professional. Never attempt to troubleshoot electrical errors, such as the condensing unit, yourself.

Air-Rite Heating & Cooling Is Your Leading Provider Of HVAC Services

With over 60 years of dependable and reliable HVAC services, Air-Rite Heating & Cooling is a team you can trust. We maintain the highest standard of customer service with true workmanship, efficiency, and quality work. If you’re experiencing air conditioning issues, contact our team right away and get the best-in-class service you deserve.

We perform exceptional HVAC installation, air conditioning maintenance, and ac repair across The Greater Chicago land area including Burr Ridge, Wheaton, Huntley, Aurora, Vernon Hills, Naperville, and more.

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