Knowing how to fix common HVAC problems is a skill set mostly left to professionals. However, there are a few concerns you may be able to tackle, like cleaning filters and checking your thermostat. We provide you with examples below. There’s one thing we can say with certainty; HVAC Maintenance, whether it’s a furnace repair or AC repair, is imperative. 


HVAC (heating, ventilation, and air conditioning) systems are essential for maintaining a comfortable living environment, whether it’s at home or in the office.

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In this article, we’ll discuss how to fix common HVAC problems and whether they should be left to professionals like Air Design Services Heating & Cooling of London and Strathroy, ON, areas.

  • Dirty or Clogged Air Filters – This is a homeowner job or ✅ ⛔ a professional job

One of the most common HVAC problems is a dirty or clogged air filter. Air filters play a crucial role in maintaining indoor air quality by trapping dust, dirt, and other particles that can affect your health. When the air filter is clogged, it restricts the flow of air, which can cause the HVAC system to work harder and consume more energy. A homeowner can easily learn how to fix this common HVAC problem.

  • Clean or replace the air filter. (mostly, people simply replace them) 
  • If you have a reusable filter, clean it according to the manufacturer’s instructions. 
  • If it’s a disposable filter, replace it with a new one. 
  • It’s recommended to change or clean the air filter every three months or as recommended by the manufacturer.
  • Note (take a photo of) the direction of the install arrows on the old filter.

  • Thermostat Malfunction – This is a partial homeowner job or ✅ ⛔ a professional job

If your HVAC system is not turning on or is not heating or cooling properly, the problem could be a malfunctioning thermostat. A faulty thermostat can cause the HVAC system to run inefficiently or not at all.

  • First, check the thermostat settings to ensure it’s set to the correct temperature and mode (cooling or heating). 
  • If the settings are correct, try replacing the batteries in the thermostat. 
  • If that doesn’t work, you may need to replace the thermostat altogether.

  • Refrigerant Leaks – This is a ⛔ professional job

Refrigerant is the substance that cools the air in your HVAC system. If there’s a leak in the refrigerant line, it can cause the HVAC system to blow warm air or not cool the air at all. A refrigerant leak can also cause the compressor to overheat and fail, leading to expensive repairs. This job is not included in a homeowner’s know-how of how to fix common HVAC problems.

  • You need to hire an HVAC professional to find and repair the leak. 
  • They’ll also need to recharge the system with the correct amount of refrigerant.

  • Dirty or Malfunctioning Condenser Unit – This is a ⛔ professional job

The condenser unit is the outdoor unit of the HVAC system responsible for releasing heat from the refrigerant. If it’s dirty or malfunctioning, it can cause the HVAC system to work harder and consume more energy. You may also notice that the air coming from the vents is warm or not as cold as it should be.

  • Turn off the power to the AC unit.     
  • Check the condenser unit for debris such as leaves, dirt, or grass clippings. 
  • Clean the unit with a garden hose and remove any debris. 
  • If that doesn’t work, you may need to hire an HVAC professional to inspect and repair the unit.

  • Clogged Drain Line – This is a homeowner job or ✅ ⛔ a professional job

The drain line is responsible for removing the condensation that forms in the HVAC system. If it’s clogged, it can cause water to back up and damage the HVAC system or surrounding areas.

  • You can use a wet/dry vacuum to remove the clog or use a mixture of bleach and water to clear the line. 
  • You can also hire an HVAC professional to perform regular maintenance and prevent clogs from occurring in the first place.

  • Ignition or Pilot Problems – This is a limited homeowner job ✅⛔ or professional job

If the issue is minor, such as a dirty thermocouple or air filter, a homeowner can likely handle it with some basic knowledge and the right tools. However, if the issue is more complex or involves gas lines or electrical components, it is best left to a professional to ensure safety and proper repair.

  • Check the gas supply: Ensure that the gas supply to your HVAC system is turned on and that the gas valve supplying your furnace or boiler is open.
  • Check the pilot light: If you have a standing pilot light, make sure that it is lit. If it is not, follow the manufacturer’s instructions to relight it. If you have an electronic ignition, check to see if it is sparking correctly.
  • Inspect the thermocouple: The thermocouple is a safety device that senses the presence of a flame and shuts off the gas supply if the flame goes out. If the thermocouple is dirty or damaged, it may not function correctly. Clean it or replace it if necessary.
  • Check the air filter: A dirty air filter can cause a variety of problems, including pilot light issues. Make sure that your air filter is clean, and replace it if necessary.
  • Call a professional: If you have followed the above steps and your HVAC system is still not functioning correctly, it is time to call a professional. HVAC systems are complex and potentially dangerous, so it is recommended that a licensed professional handle any repairs or maintenance.

What is the most common part to fail on your HVAC system?

The most common part to fail in HVAC systems is the capacitor. 

  • Capacitors are electrical components that store energy and release it to start the motors that power the compressor and fan in the air conditioning system. 
  • Over time, capacitors can degrade or fail due to various factors such as age, heat, voltage surges, and other electrical issues.

When a capacitor fails, it can cause a variety of HVAC problems, including:

  • The HVAC system won’t turn on
  • Air conditioning or heating is weak or not blowing at all
  • AC compressor won’t start
  • The fan motor won’t start
  • AC system is making a buzzing or humming noise

The good news is capacitors are relatively inexpensive to replace and are a standard part of regular HVAC maintenance. 

  • However, it’s essential to have a trained HVAC technician diagnose and repair any capacitor issues, as electrical components can be dangerous and require specialized knowledge and tools to work with safely. 

How to fix some common HVAC problems can be learned by homeowners; others require the expertise of a professional HVAC technician.

Refrigerant leaks, condenser unit malfunctions, and ignition or pilot problems require specialized tools, licenses, and knowledge to diagnose and repair.

Additionally, HVAC systems are complex and interconnected, so a problem in one area can affect the entire system. For example, a clogged air filter can cause the HVAC system to work harder and consume more energy, which can lead to premature wear and tear on other components. A professional HVAC technician can perform a comprehensive inspection and identify any underlying problems that may be affecting the system’s performance.

At Air Design Services, we provide comprehensive HVAC services, including installation, repair, and maintenance. Our team of certified and experienced technicians can diagnose and repair any HVAC problem promptly and efficiently, ensuring that your system is functioning correctly and maintaining your indoor air quality.

In conclusion, some HVAC problems can be addressed by homeowners, and it’s essential to recognize when a problem requires professional expertise. 

Contact Air Design Services to schedule an appointment near London at (519) 963 0572 or near Strathroy at (519) 246 1224 and ensure that your HVAC system is functioning correctly and keeping your home or office comfortable and healthy.