• September 08, 2021

Home inspectors are trained to visually inspect and evaluate residential air conditioning and heating systems (HVAC), as well as all of the other parts of your home. When they perform their home inspections, they typically find problems with air conditioners and furnaces. Here are the top 10 common HVAC problems that are revealed in most home inspection reports.

1. Dirty Filters & Components

Dirty HVAC systems are the number one defect noted with most home inspection reports. The central mechanical part of the HVAC system uses a lot of energy. As a result, it changes temperature often, as its fans blow and suck air over and over again all day long. This airflow gathers dust over time that needs to be cleaned out regularly.

We recommend having an HVAC company clean your furnace and air conditioner on a scheduled basis. In addition, the air filters should be replaced every three months, or sooner. This maintenance will ensure that the system is not contaminated with debris. In addition, it will extend the life of your HVAC system by keeping dust out of the bearing, seals, and motors.

2. Lack of Maintenance

HVAC systems require routine maintenance that homeowners often overlook. In addition to cleaning the system and its components, belts, bearings, and seals are often in need of care.

We recommend that you have a licensed HVAC specialist perform a full inspection of your HVAC system at least once a year to spot any of these issues before they become more serious. If you can identify worn-out components before they fail, you can extend the life of your heating and air conditioning system by many years.

3. Mechanical Components Worn Down

Even with all of the cleaning and maintenance mentioned above, HVAC parts will eventually wear down. For example, fan bearings start to squeak and rattle, ductwork can vibrate and come loose, and units can become unlevel over time.

It is wise to replace any mechanical parts that are worn down as soon as you can. A service technician can follow a preventative maintenance program to cut down on costly service calls. The longer a part operates in disrepair, the more damage it will cause over time. When these components fail, they typically end up in the inspection report as a defective item.

The heat exchange is one of the most costly parts of the furnace to replace. Make sure to have an HVAC technician look at yours for cracks in the housing.

4. Refrigerant Leak

When refrigerant leaks out of your air conditioner, it can contaminate the refrigerant lines and cause costly repairs later. This issue is one of the most common air conditioning problems. You can have a leak test performed on your system to determine if any small leaks are visible in the pipes.

This problem may be the issue if your air conditioner is blowing cold, but not quite as cold as it used to. Home inspectors look for evident and easy-to-spot leaks within the amount of time they have. Air conditioning mechanics will spend much more time to find a leak if you hire them directly.

5. Inefficient Duct Work

Ductwork seems like a simple part of the HVAC system that shouldn’t need any extra work. This assumption is valid, assuming that nothing has been changed or moved. It’s also assuming that the ductwork was correctly installed in the first place.

Home inspectors will look for leaks in the ductwork and tears and abrasions in the connections. Unfortunately, if the ductwork is leaking or pinched, it can mean unnecessary work for your HVAC system. Fortunately, if there are issues with the ductwork, they are typically easy and inexpensive to fix.

6. Damaged Flue

The flue on the furnace is designed to vent carbon monoxide. Therefore, it must be in good operating condition to avoid poisonous gas leaking into your home. In addition, the flue can be easily bent, which might restrict or divert airflow in the wrong direction.

Home inspectors often look at the flue connection to the furnace to make sure that it is bonded and installed well. Then they will check to make sure the flue pipe is pushing exhaust to the exterior of your home without any leaks in the line.

7. Unlevel Pad

The outdoor concrete pad that the air conditioner sits on may shift to an unlevel state over the years. This pad needs to stay level to keep the fan balanced and all of the components in order. The more unbalanced an air conditioner pad becomes, the higher likelihood the unit will experience issues.

Home inspectors typically check the air conditioner pad to ensure it is level when performing a home inspection. Therefore, it’s common for this issue to end up in an inspection report on older homes.

8. Dirty Condenser

Condenser coils are vital because they condense the vapor refrigerant to a liquid state to work in the unit. If the condenser coils become damaged, the air conditioning unit will have a hard time staying cool. In addition, a broken condenser unit can cause the central system to overheat and be replaced, which is very costly.

Condenser coils are easy to inspect visually. However, if you notice that your coils are dirty and try to clean them yourself, be careful. Be sure to turn your circuit breaker off before cleaning it. Condensors can get damaged very easily. Also, don’t put too much pressure on them and avoid bending the vents.

9. Dirty Evaporator Coils

All of the warm air brought from your return ducts goes through your evaporator coil. This process makes it highly susceptible to debris and damage. When an evaporator coil fails, the unit will start to freeze up. It can shut the entire system down and cause irreparable damage.

Home inspectors will note issues with the evaporator coil if they notice frost around the unit. But, again, this is a common repair that needs to be dealt with quickly if it comes up in an inspection report.

10. Improper Condensation Drainage

Air conditioning units produce a lot of condensation, which needs to be routed and drained to the proper locations. If condensation drainage is blocked or backed up, it can cause water damage all around the HVAC unit. This scenario is awful when the unit is located in the attic.

One of the most common issues that inspectors look for is water buildup in the AC drain pan. If there is pooling water, the pan is likely clogged and needs to be cleaned. In addition, this condensation needs to be drained to keep from spilling over into the walls and ceiling. Finally, the condenser drains into drain lines that need to be cleaned out every so often. This issue is an easy problem to fix, so be sure to take care of it immediately if you spot it.


Home inspectors are not as knowledgeable about HVAC systems as an HVAC service specialist who works on nothing but those units every day. However, inspectors are experienced enough to find clues that can detect issues early in their development. For this reason, home inspectors are very valuable to the life of your heating and cooling systems.

If you have recently had a home inspection performed, I hope this article gave you a good insight into the issues involved with residential HVAC systems. I recommend tackling any problems as soon as you know about them to keep your system in good health and avoid costly repairs later.

Andrew Fortune

Hi! I'm Andrew Fortune, one of the founders of Tagzter. I also own and operate a real estate brokerage in Colorado Springs. I enjoy writing about the home inspection industry and its relationship with the real estate industry. I also enjoy discussions about SEO, digital marketing, video marketing, website building, mobile app development, and all things Internet. Feel free to reach out to me anytime.