5 reasons Why AC Smells Like Vinegar

The cold air of the house is the welcome retreat on the hottest summer days unless the AC smells like vinegar. Most uncommon smells coming from the air conditioner such smells like vinegar, dirty socks and rotten eggs.

ac smells like vinegar

These issue indicates that there might be some problems with the air of your AC. So, it’s necessary to find out the cause and solve the problems. Many problems easily done the house owners but only few problems need professional help.

Common Reasons- why the AC Smells Like Vinegar:

Well, there are various issue through which the AC smells like vinegar. For this purpose, you have to investigate that why it happens and what it’s major cause. In various cases, you can easily solve this problem by yourself. If you think you can’t solve this issue on your own, get in touch with a qualified HVAC expert.

Ac smells like vinegar because it happens that this odor cause by:

  • Mold or bacteria.
  • Electric motors.
  • Dirty Air filters.
  • Too much condensation.
  • Blocked or clogged condensation pan.

Mold or Bacteria:

One of the task of the air conditioner is to dehumidify the air of your house. All the humidity is collected and removed from the air and then drained away from your house. Malfunction AC can easy cause your air conditioner parts remains damp, which is the best place for the mold to grow.

Mildew, mold and the growth of bacteria inside the house ductwork through which sour smells emits.

Excess amount of condensation which is produced by your AC and the improper system of drainage increases the moisture and allow the mold to grow in ducts. Moisture and growth of mold is caused by the improper sealed air ducts means the air conditioner is so much larger as compared to the square footage of the house and due to keeping the thermostat of air conditioner at low temperature.

Solution of this problem

You have to check the ducts to ensure that excess amount moisture or mold are present or not. If the molds are present, then it will be removed properly. For this task hire a professional for cleaning services and ensure that molds are properly removed or not.

Furthermore, you have to check that there’s should be no leakage in the ducts which is the main cause of mold growth. Also, check that thermostat is not set at very low temperature. You can do this task by yourself or you can hire professional.

If you want to do this task by yourself then firstly, turn off your AC through switch and thermostat. Open the indoor unit access panel of air handlers in order to check the drain pans for excess amount of water and for mold growth. Drain pans are easily cleaned by your hand but it is one the best option to replace the pan in which excess amount of mold are present. Also, mold can easily grow on the internal parts of the systems like evaporator coils.

By following the manufacturer’s directions, you can easily clean the evaporator coils with the help of no rinse cleaner of evaporator coils or clean with compressed air. If you feel that such task is very difficult to perform then hire a professional.

Electric motors:

All the electric motors during performing normal tasks emits ozone naturally which is inorganic molecule. Ozone is having very strong smell which is produced by the usage of electricity. Damaged or broken motors produces extra amount of ozone instead through which you can easily notice this smell. Ozone also contains very harmful chemicals which is very bad for our heath. That’s why you notice that your ac smells like vinegar.

electric motors

Solution of this problem:

Hire a professional technician for the complete inspection and repair or replace the broken or damaged electric motor if necessary. If you are going to inspect air conditioner by yourself. Then, firstly turn off the air conditioner through switch and breaker panel.

Visually, inspect all the wiring which is present near your motors. In AC motor there are many parts which contains high voltage. Therefore, avoid fiddling with your air conditioner. If there’s any wiring issues then, hire a HVAC professional for repairing.

Too much condensation:

Basically, condensation normally produced by the air conditioners during cooling cycle. The AC evaporator coils are filled with refrigerant, when all the warm air passes through the evaporator coils the refrigerant absorb the heat and turn the hot air into cool air.

After the whole process the cold air moves towards your house with the help of vents/ ducts. Such condensation builds up on the evaporator coils and then collect in your ac drain pan. Then, it moves out through drain line. Sometimes you will face a problem like air conditioner leaking water.

All this happens due to dirty air filters. Because air filters with full of dirt or debris reduces the flow of air and also reduces the evaporation. Remember excess amount of condensation develops in that environment where humidity level is high.

too much condensation

Solution of this problem:

Change your air filter and regularly change the air conditioners filters after 30 to 90 days. Clean your ac evaporator coils because it’s helpful in reducing the condensation. Hire a HVAC professional for cleaning the coils or you can easily clean the coils by yourself.

Firstly, turn off the air conditioning unit and remove the air handler access panels which is present in the indoor unit. Follow the manufacturer’s directions and clean the coils with the compressed air or you can clean the evaporator coils easily with no rinse cleaner.

Dirty Air Filters:

Basically, dirty air filters clean the air which is present in your house before entering in the air conditioner. Because air filters catch all the contaminants which present in the air.

If you are not changing the air filters regularly then as time passes the flow air decreases due to blockage. Also, humidity and formation of mold increases and strong sour smell is coming from the air filters that’s why you notice that your ac smells like vinegar.

Solution of this problem:

Always, ensure that your air filters are placed in the accurate position if you don’t know which way does the air flow in furnace. So, firstly place it in the correct position. If you notice that the air filters full with dirt and debris, then replace your air filter immediately. Well, I again mentioned change your air filters after 30 to 90 days for the better performance. So, you have to know that how often to change air filters of the air conditioners. All its depend upon that which type of filters you are using. Well, it depends on a number of variables. General rule is change your air filters after 30 to 90 days.

Blocked or clogged condensation pan:

Condensation normally collects the moisture which drips off from the evaporator coils. This drain pan empties via the drain pipe. But sometimes the drain line is blocked due to hair, dirt and debris which blocked the drain line. So, in result the water remains stay in the drain pan. In this stagnant water growth of mold increases. also, refrigerant leakage make your ac freezing up and unable to perform its functions.

Clogs normally occur when you leave your air conditioning unit unchecked and it’s covered with dust and debris and not doing its proper maintenance or run it without the air filters.

Solution of this problem:

Turn off the power of AC unit and open the air handler access panel which is present in the indoor unit. If you find excess amount of water or growth of molds, then replace the air conditioner drain pan. Otherwise you will face the problem like your ac smells like vinegar. Well, you will find primary drain-pan under your ac evaporator coils and over-flow drain pan is located below your ac primary pan which is present under the air conditioning unit. On the other hand, clean it with the hot water or use paper clip with the wire in order to unclog the condensate line.

Other smells in the air conditioners:

When your ac smells like vinegar, it’s very hard to cop up with this because smell of vinegar is very unpleasant. But, sometimes the air conditioners release many Foul smells in the house. Such stinky smells are:

  • Musty smell.
  • Rotten eggs.
  • Dirty socks.
  • Burning smell.

When you leave the wet towels for longer period of time in the washing machine then a type musty smell come and exactly same smell comes from the air conditioner. Because the one task of air conditioner is to remove the humidity from the house air, because mold, fungus and mildew thrive in the moist environments.

It’s possible that musty smell which is coming from the air conditioner is due to mold or fungus growth in the outdoor or indoor unit or present on your indoor AC components. Most common causes are clogged or blocked drain pan, air filters and drain line. Mold can easily grow in the improper sealed ductwork.

All the ac parts must be cleaned properly in order to avoid the mold and fungus from coming back.

Rotten eggs:

If you notice rotten eggs smell, then it means gas leaks. Well, I know that there’s no smell in the natural gas but having a stinky little bit smell for people’s alert that gas is leaking. Firstly, repair the gas leakage by contacting with the gas company. Leave your premises until its again safe for living.

Rotten eggs smell like the smell is coming from the dead animal. Also, sometimes few birds find the shelter and starts living near or in the ductwork. So, it necessary to clean all the ducts remove the animal carcass. Also, properly sealed the ducts in order to prevent any recurrence in future.

rotten eggs smell

Burning smell:

Burning smell usually comes from the vents which indicate that there might some electrical issues. Such electrical issues occur in the old air conditioning units instead of new ones. The major causes of this issue is: broken circuit boards and burned out electric motor. Contact with HVAC professional who can identify and easily solve this problem by performing essential repairs.

burning smell

Dirty socks:

Smell of the dirty socks is very familiar. So that’s why HVAC professionals refer jokingly called it as a dirty socks syndrome. This smell usually caused by the mold and bacteria which is present in the moist areas like on the evaporator

Coils or in the drain pan. Dirty air filters and blocked drain pan lead towards the excess amount of moisture and increases the growth of mold.


If your ac smells like vinegar and various smells like rotten eggs, musty towels, dirty socks smell and burning smell is coming from the air conditioner then it’s mean that your AC needs proper maintenance or repairing. Many smells increase due to the growth of fungus mold and mildew. And other complex smells due to electrical issues or smell coming from the dead animal and due to gas leakage. I hope you get answer why your ac smells like vinegar.

Luckily, some DIY solutions are present in order to solve such issues like:

  • Change your AC air filters.
  • Inspect the growth of mold, fungus and mildew in the ducts or in indoor unit components, drain pan etc.
  • Clean your air conditioning evaporator coils.

Electrical and various complicated problems should be easily solved by the professional HVAC technicians.

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