AC Smells Bad When Turned On

If your air conditioner starts blowing smelly air throughout your home, sometimes no amount of cool air can make you feel comfortable. It can quickly make living indoors feel miserable. In some cases, bad smells from your AC can even be dangerous and require immediate professional attention. But what causes these odors, and what can you do to get rid of them?

5 Reasons Why Your AC Smells Moldy

1. Dirty Air Filters

It is the natural job of air filters to collect dust and other particles from the air, but if these filters are not properly replaced at the appropriate intervals, mold and mildew can collect on them, spreading foul odors throughout your home. Dirty air filters will also hinder the performance of your air conditioner and can lead to many other problems. For these reasons, it is vitally important to check and replace your air filters as part of your routine maintenance.

2. Dirty Evaporator Coil

Another common cause of bad AC odors is a dirty evaporator coil. The evaporator coil is where the liquid refrigerant is turned to gas so that cool, refreshed air can blow throughout your home. In some cases, however, excess moisture can develop on these coils, causing mold and mildew to grow. Sometimes, you can clean these coils yourself, although it’s never a bad idea to call a professional. Simply locate the coils, which are usually positioned inside an access panel inside or nearby your air handler (the inside unit), and clean them with a soft brush and mild detergent mixed with warm water.

3. Problems in Your Ductwork

If your air ducts are damaged or have leaks, outside pathogens can enter and create mold and mildew, which will produce bad smells throughout your home. Signs of leaky air ducts include inconsistent cooling from room to room as well as problems cooling even after running the AC for long periods of time. While it’s possible to patch small tears yourself, it’s generally better to call an HVAC technician. They are able to clean the ducts with specialized, safe equipment and seal them against further leaks and damage. They’ll also be able to inspect the system for other problems that may be present.

4. Clogged Drain Lines

Clogs in your condensate drain line can cause a myriad of microorganisms to develop, such as algae, mold, mildew, bacteria, and more. These drain lines are meant to remove excess moisture from your unit during its heat exchange process, but malfunctions, damage, and regular wear and tear can cause problems to occur. For most clogs, you can fix the problem yourself with a few common household items and a little bit of effort. More serious drain line problems may require the help of a professional, however.

5. Stagnant Water in Drain Pan

If drain lines become clogged, water can build up within the AC drain pan itself. Stagnant water is a ripe environment for fungal growth, mildew, and many other unpleasant things. If you notice standing water in your AC drain pan, remove it with a towel or wet/dry vac and clean the pan with vinegar, bleach, or similar cleaning solutions. However, your drain pan itself is probably not the issue, so you will need to unclog your drain line or call a professional to troubleshoot the underlying problem.

2 Other Bad AC Smells and Their Causes

6. AC Smells Like It’s Burning

If your AC unit has been inactive for a long period of time — such as the first time you turn the heater on for the cold season — it’s totally normal for a burning smell to occur for a short amount of time as the unit burns off dust that has settled throughout the period of inactivity. This should go away after the first few uses. If your unit hasn’t been inactive, or if the smell is particularly strong and/or does not go away, you may have a more serious problem requiring professional assistance. AC units contain many electrical components, and it’s possible for these to burn. Do not try to troubleshoot this problem yourself — call an HVAC professional.

7. AC Smells Like Chemical Fumes

If you’re smelling strange fumes when your AC is running, it could be due to a refrigerant leak. Refrigerants, such as freon, are what allow your air conditioner to cool the air that gets distributed throughout your home during a cooling cycle. These chemicals work great for air conditioning but are toxic when direct exposure occurs. Inhalation of refrigerant can lead to refrigerant poisoning, which has many harmful effects and can even be fatal.

If your AC unit is emitting chemical or exhaust-like fumes, turn your system off and contact an AC professional immediately. If you’re experiencing any difficulty breathing or have had any direct exposure to refrigerant, seek emergency medical help or call the National Poison Control Hotline at 1 (800) 222-1222.

Improve Your Air Quality With Complete Air Mechanical

At Complete Air Mechanical, we have experienced HVAC professionals who can ensure energy efficiency for your home or business. We provide services in Orange, Osceola, Seminole, and Volusia counties, and we offer financing options.

Call us at (407) 915-0144 and let us help you keep energy costs down.