UNPLEASANT ODORS FROM AIR CONDITIONING UNIT

Are you experiencing a musty odor coming from your HVAC system?

If this is the case, then you have landed in the perfect spot to discover a remedy and eliminate any unpleasant odors in your home.

One of the initial steps to take is inspecting the air filter as it is usually the root of the problem.

A clogged and dirty air filter can indicate a plugged evaporator coil due to the accumulation of dirt, dust, and potential bacterial growth.

Bacteria will be sustained by standing condensation, preventing it from dripping off the evaporator coil and into the drain pan. This is the primary cause of unpleasant odors in your home when your HVAC unit is in use, commonly referred to as "dirty sock syndrome" in the HVAC industry.

When the evaporator coil becomes clogged, it can result in stagnant condensation and a musty odor caused by the air passing through the buildup. To solve this issue, it is necessary to chemically clean the evaporator coil.

Steps for Cleaning an Evaporator Coil

- Begin by turning off the air conditioner and taking out the filter.

- Ensure your safety by putting on safety glasses and chemical resistant gloves.

- Use a bristled brush, such as a toilet brush, for this task.

- Brush the evaporator coils in the same direction as the coil, typically up and down.

- Avoid brushing side to side to prevent bending the coil fins.

- Apply coil cleaner to the evaporator coils, preferably with a pressurized pump sprayer.

- Brush the coils once more.

- Rinse the coils with hot water.

- Continue this process until the coils are clean and shiny.

- Don't forget to clean up any mess you made.

The next step in eliminating a foul-smelling air conditioner is to inspect the drain pan and, if needed, clean it. If the coils were found to be dirty, it is probable that the drain pan is also affected.

Steps for Cleaning the Drain Pan of a Furnace

- First, switch off the power to the unit.

- Apply the coil cleaner and use a small, soft toilet brush to scrub the drip pan.

- Use a wet/dry shop vacuum to remove any remaining water.

- To prevent clogging, flush the pan with hot water.

- Finally, wipe down the insulation and all components inside the air handler/furnace.

Certain tabs are designed specifically for use in air conditioner drain pans with the purpose of inhibiting or reducing the growth of bacteria. However, I have not come across a product that effectively fulfills this function. Nonetheless, some tabs do emit a pleasant fragrance.

In most instances, performing these two checks can eliminate the unpleasant odors caused by air conditioner or the infamous "dirty sock syndrome".

Are You Still Experiencing Unpleasant, Damp Odors from Your Air Conditioning Unit?

Perhaps it is time to take action and seek assistance from a professional service. If you are a novice in the field of HVAC and unsure of where to turn, continue reading, my young apprentice.

Inspect the blower motor wheel for indications of bacteria and accumulation. An accumulation of dust on the blower motor wheel can lead to unpleasant smells in your HVAC system. A heavily clogged blower motor wheel can also result in instability and imbalanced spinning, ultimately reducing air performance.

Steps for Cleaning an Unclean Indoor Blower Assembly (Professional Recommended)

- Unscrew and detach the blower motor assembly.

- Bring the blower motor assembly outdoors.

- Detach the motor from the blower motor casing.

- Loosen the set screw to remove the wheel from the blower motor shaft. In some cases, older motors may be stuck on the shaft and require lubrication and a motor pulley to disconnect the wheel.

- After removing the blower motor wheel, use coil cleaner and a garden hose to clean it.

- Once it is clean and shiny, reinstall the blower motor assembly.

In most cases, following these instructions can effectively eliminate unpleasant odors from your air conditioner, including the infamous "dirty sock syndrome".

However, if the issue persists, it may be necessary to have your air ducts examined and potentially cleaned.

Tips for Avoiding Bacterial Growth in Your Coil

In case the odor from your air conditioner disappears after utilizing chemical cleaning on the evaporator coil and drain pan, there is a possibility for the return of the infamous "dirty sock syndrome".

However, there are a few alternatives available to prevent or slow down this issue. For optimal results, increase the MERV rating of your air filter to the maximum level that your system can accommodate.

According to some specialists, the placement of Ultra Violet lamps both before and after the coil can effectively eliminate all types of bacteria growth on the evaporator coil. While this method is beneficial, it is not a foolproof solution.

If you have exhausted all of the aforementioned solutions and the unpleasant odor from your air conditioner persists, it may be necessary to replace the evaporator coil and apply a coating to prevent bacterial growth. Unfortunately, this is also the most costly option. If your air conditioning system is over 10 years old, it may be worth considering replacing the entire unit.

Scent of Burning Coming from Air Conditioning Unit

There are various types of odors that may emit from your air conditioner furnace, typically when you initially activate your heater for the season. The accumulation of dust on your blower assembly, gas furnace tubes, or electric heater can cause this burning smell. Once the heat is turned on, the odor will dissipate after a few minutes.

Another type of burning odor could be caused by burning wires. You will immediately notice the strong smell of wire or duct insulation. This may also be accompanied by smoke and could potentially lead to your furnace failing. In this situation, it is best to seek professional service.

If you notice smoke coming from your vents, it may be necessary to call emergency services.

Concluding Remarks on Unpleasant Odors from Air Conditioners

As a technician, if you receive a complaint about an air conditioner emitting a musty smell, it is highly likely that you are dealing with dirty sock syndrome. There are various possibilities for the cause of unpleasant odors from your air conditioner that have not been addressed in this article.

For instance, I have encountered dead rodents behind an air return grill that did not emit a musty or burning scent, but rather a foul one.

Do you have any experiences or worries to share regarding unpleasant odors from air conditioners? Leave a comment or attach a picture below to start a discussion!