HVAC Repair Tips


Pest infestation of your HVAC system means double trouble. That’s because pests in the ducts will contaminate the indoor air causing various health problems and they can also damage your air conditioning system, especially the ductwork. Of course, this problem is a huge concern in summer, but many critters and birds make this a problem in winter as well. The best way to deal with this is to notice the signs and call in HVAC repair services. Here is a guide for you.

Which Parts Of The HVAC System Are Affected

Pests and rodents mostly take shelter in the ductwork or the outdoor unit of your air conditioning system.

Why Are Pests And Rodents Dangerous For Your Health And Your HVAC System?

Air Ducts

If they are in the air ducts, they can contaminate the indoor air which can cause health problems. The health concerns are more serious for people with allergies to insects or rodents. Moreover, if you use pesticides on them, this can also backfire and lead to bad indoor air quality and health issues. Additionally, pests and rodents can also die in the ducts causing your house to stink.

Apart from that, these critters and pests also build nests that damage your air ducts and your air conditioning system. With nests and the rodents themselves, the airflow is impacted which puts stress on the unit. If not fixed, the unit might break down sooner than expected. Plus, these creatures can also damage the ductwork leading to leaks that will impact the performance of your AC. There will be airflow problems with this as well.

Outdoor Unit

Mostly, lizards, squirrels, mice, raccoons, and others try to take shelter in the outdoor unit of your HVAC system. There may be fewer health concerns when they infiltrate the outdoor unit as compared to the air ducts, but the damage they incur to the air conditioner is substantial.

Firstly, even if they only reside there and build a nest, this will block the fan and affect the heat dissipation process of the outdoor unit.

However, if they chew through coils and wires, then it becomes even more complicated and costly. They can damage the fan, fan motor, compressor, condenser coils, and wiring. This can lead to many problems. For example, if the condenser coils crack, the refrigerant will leak. Due to this, the AC won’t cool properly and over time, it will lose its ability to cool until you have the cracks fixed and refill the refrigerant. This is an expensive process.

Signs Of Pests Or Rodents In Your HVAC System

Tracks Or Droppings

The insides of the air ducts are not visible so you will need to use a flashlight and take a look inside one of the vents. If there are pests or rodents, you will see tracks, droppings, or unexplained marks.

Scratching Noises

You will hear scratching or similar noises when rodents or pests move on a metal surface. These noises can be difficult to hear in the daytime, but at night you may be able to hear them quite clearly.

Holes In The Ductwork

Holes or cracks in the air ducts can occur due to multiple reasons. They can occur because of age or improper installation, but one reason for this can also be pests or rodents making these holes. So, combine this sign with other signs mentioned here to make sure.

Stains And Smudges In The Air Ducts

Stains from roaches are visible from a flashlight as they leave these stains where they live and crawl. However, some others leave stains that can only be seen with a backlight like smudges left by mice. However, even in the case of mice, you will be able to see their droppings as mentioned earlier.

Debris Or Chewed Stuff

Birds like to take some debris with them where they like to build a nest. Some other small mammals also do this. So, look for something that shouldn’t be in the air ducts. Moreover, squirrels, mice, etc., take things and chew them. There will be chewed stuff. Moreover, some parts of the air ducts or the outdoor unit casing may be chewed as well.

Bad Odor

This is a major sign that doesn’t even need an inspection because you will be able to notice bad smells, especially when you’re near the vents. Any foul odor from the vents means there is either a living thing(s) in your ducts or there is mold or a leakage.

Various pests and rodents leave their unique smells. For example; mice leave an ammonia-like smell where they live. Roaches usually leave this damp oil odor.

Cockroach Skin And Eggs

Cockroaches shed their skin so it’s easy to notice it in the air ducts. Moreover, cockroaches also leave egg capsules. They look like small brown shells.

Once you notice these signs, consult an air conditioning expert because spraying pesticides in air ducts is not suggested. The AC technician will inspect the HVAC system and then repair and clean the ductwork and the outdoor unit along with other parts like the air handling unit.

How To Prevent Pests And Rodents From Getting Into Your HVAC System?

Seal The Ductwork

Leaving cracks and holes after HVAC installation or any other home improvement project can give mice and others an entry point to your house. So, seal everything including the ductwork after the HVAC installation.

Regular HVAC Inspection

Regular inspection is stressed by everyone because it’s that vital for the longevity of your HVAC system. Have the entire HVAC system inspected once or twice a year to detect any cracks and seal them or detect any pests and clear them before they multiply and become a major problem.

Similarly, the inspection will also include the outdoor unit. There can be debris and leaves that can become a perfect place for birds and small mammals to live. So, cleaning them can keep them from making your outdoor unit their new home.

Air Ducts Cleaning

An inspection gives you insight into what’s the condition of the ductwork. Depending on what’s required, the expert may suggest you have the ductwork cleaned. When it comes to that, don’t delay it because thorough cleaning will remove debris buildup which can be an attraction for pests and rodents. As explained earlier, ductwork cleaning will also remove dead or alive pests from the ductwork.

Install A Wire Mesh Screen On Every Exhaust Vent

Open exhaust vents that don’t have anything on them to prevent rodents, birds, and pests are an excellent entry point for them into your house. So, cover them with wire mesh screens.

Keep Other Parts Of Your House Sealed

There are some parts of a house that rodents and pests use as an entrance like the pipes on the roof, attic vents, gaps in windows or ceilings, unsealed drain pipes, uncapped chimneys, etc. So, keep all these parts of your house sealed and repaired, and inspect them regularly.


Pests or critters in an HVAC system can cause a lot of problems if ignored. You can use the tips above to determine if your HVAC system is infested with them to consult HVAC companies Chantilly on time. Moreover, follow the best practices mentioned above to prevent them from infiltrating your HVAC system again.


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