Mini Split Smells Like Vinegar -What’s Wrong?

There are only a few things in this world that should smell like vinegar, and a mini-split is not one of them. The smell is already quite bothersome, and if it spreads throughout the house, it is more troublesome. You have already confirmed the source, but what to do next? Don't fret! We've identified the cause and several solutions to your problem.

There are two reasons why your mini-split smells like vinegar:

  • A refrigerant leak or low cool air concentration: Inspect your system and seal any holes and tears, then refill the coolant to the standard level if needed.
  • Electrical problem: This could be hard to diagnose; thus, it is better to hire an HVAC professional.

Keep reading as we discuss other familiar smells of mini splits and tips on how to improve its performance. We will also be answering some of the frequently asked questions related to this topic.

Air conditioner (AC) indoor unit or evaporator and wall-mounted, Mini Split Smells Like Vinegar -What's Wrong?

Reasons Why Air Conditioner Smells

Air conditioner

In most appliances, especially electrical types, odors are usually a tell-tale sign that there is something wrong with it. There's a chance that your mini split might already have an issue, and the system intensified the smell due to the severity, enough to catch your attention.

Vinegar or Sweet Smell 

A vinegar or sweet smell signals that there's a tear in the refrigerant line and the coolant is leaking. Aside from the smell, slow cooling time or failure to lower the room temperature is another sign of this issue. Seal up any tears and refill the coolant to the standard measure if needed. 

Burning or Electrical Smell

This smell requires immediate attention from out of all the odors since any electrical and burn-related smell can be a fire hazard.

There are four possible causes which are:

  • Failing Motor
  • Damaged Wiring
  • Overheating
  • Components Melting

Once you notice the smell, turn off the system and check the surrounding area for soot and smoke. Call a technician to inspect your AC and fix the problem when everything is clear. It is best to leave this to the professional because the mini split's wiring and mechanisms are complicated, and meddling with it may result in further damage.

Fishy or Rotten Smell

Better prepare yourself for the possibility of seeing a dead animal in your mini-split. It is gross as it may seem, but it is common for little animals, like rats, to get stuck in the system and die there.

Usually, this issue will only be detected once the smell magnifies or when it's already rotting. There's no other solution for this except for deep, thorough cleaning. You can do it yourself or hire a professional to do the job for you. Either way, you need to ensure that the carcass has been removed and no other problem arose from this.

Musty or Urine Smell

This musty smell shows that mold growth and bacteria propagate in your system. If it has already affected the air handler, the spores could circulate in the air the spread throughout the house. 

In some cases, it might smell worse and more rancid-like urine; this is due to the bacteria mycotoxin. This can be troublesome for people with allergies and respiratory problems, worsening their condition. With a fishy smell, deep, thorough cleaning and filter replacement will fix this issue. 

Don't overlook these odors because if left unattended for long periods, these may lead to more damage and costly repairs. It might even be irreparable in the worst-case scenario and needs to be replaced. Consult with technicians and schedule regular maintenance for optimum performance.

Common Mini Split Troubles & How to Fix Them

Air conditioner system on white wall living room interior

Aside from the smell, there are also other technical problems mini-splits encounter. Here are the typical troubles of mini splits and their easy fix.

It is worth noting that these are most often experienced by old units near the end of their useful life, but in some cases, new ACs may show these symptoms too. 

Blowing Hot Air

The primary purpose of ACs is to cool off the room, but if it blows out hot air instead, you might want to check all of these parts.

  • Refrigerant leak - ensure the coolant is at the standard level
  • Coils - check if it is not frozen over
  • Sensors - inspect for any damage and if still working properly
  • Circuit board - check for any broken parts

You can quickly solve the first reason by refilling it, but the remaining three might require the assistance and expertise of technicians.

Not Dehumidifying

During summer, your mini split AC serves a dual purpose as a cooling system and dehumidifier. However, something might block the condensate drain line if it fails to do the latter. Another cause may be the sizing of the unit; if it's too big for the room, it instantly lowers the temperature without dehumidifying it first.

The size and properties of the mini-split should be proportionate and complementary to your room and location. Before purchasing a unit, seek the advice of your contractor to determine what specifications suit your home.

Not Draining Water

Like the dehumidifying problem, a clogged drain line will prevent the water from draining out properly. You can quickly clear out the blocked drain line by removing any blockage or debris. 

Won't Turn On

Firstly, check the remote battery; most of the time, if it won't turn on, the battery just ran out of power. Replacing it will solve the problem; however, if not, contact your HVAC technician and have it checked out.

Making Unusual Noise

The occasional beeps, hums, and gurgles are normal, but continuous disturbing sounds are not. Don't be alarmed if you happen to hear these; these are part of the mini split's operational activities. Listed below are the typical sounds that you can hear from your unit. 

  • Swooshing, crackling and gurgling- these signals that your AC is on defrost mode
  • Popping or clicking- these are associated with the plastic casing expanding while on

However, if you notice that your aircon frequently enters frost mode, it may mean something wrong with the AC. It can be due to low coolant, damaged sensors, faulty components, etc. Due to multiple reasons, it may be pretty difficult to pinpoint the culprit; thus, we highly recommend hiring a technician.

Preventative Measures For Common AC Problems

Air conditioner blowing warm air

Often neglected, but probably one of the root causes of all problems is a dirty air filter. Ductless mini-splits don't need new filters every month, unlike the traditional HVAC system. A simple clean-up will do, and it costs less plus environmental-friendly. 

Tune-Ups or Regular Maintenance

Keep those warranty claims in a safe place and verify the terms; some manufacturers include this service together with the purchase. It will save you a ton of money, and the technician handling your unit is more knowledgeable about the model and brand than outsiders. 

A regular maintenance check and tune-up ensure that your mini split works efficiently all year round. Deep thorough cleaning and broken part replacement are some of the significant parts of maintenance checks. Moreover, they will also give tips and suggestions on how to properly care for your unit, thus prolonging its life.

How To Clean Ductless Mini Split Air Conditioners

A wall-mount mini-split heating and air conditioning unit installed in a new house.

Not everyone has the extra budget to hire a professional to clean their units. So for the benefit of those who want to save a few bucks, here's a run-through of how to clean mini-splits.

Cleaning the Outdoor or Condenser Unit

  1. Prepare the cleaning materials: rug, vacuum, soap, gloves, etc.
  2. Turn off the system.
  3. Sweep the debris on the unit and its surroundings.
  4. Rinse off the outdoor cabinet.
  5. Clear out accumulated dirt and debris inside the unit.
  6. Wash the fan casing.
  7. Clean the fan blades: observe precautions as the blades may be sharp.
  8. Drain the condensate pan.
  9. Remove blockage in the drain hose, if there's any.
  10. Allow units to air dry or wipe the moisture off.

Cleaning the Indoor Air Handler Unit

  1. Wipe the surface.
  2. Remove and clean filters.
  3. Clean evaporator coil- remove dirt and mold.

Frequently Asked Questions

Hand with remote control directed on the conditioner

What Does Freon Smell Like?

Freon is a relatively odorless chemical, but in some cases, you can detect sweetness, ether, or chloroform scents. If you notice this smell coming from your mini split, inspect the unit for any tears and holes in the refrigerant line and seal it up. Prolonged exposure to freon can harm both your body and the environment.

Can You Get Sick From Smelling Freon?

A person may develop respiratory problems and organ damage or may even cause death if exposed to freon-contaminated air for long periods. Although some claim that even slight contact with the chemical still gives off adverse effects.


Prevention is always better than cure; that is why when you notice something is off with your mini split, take action. Don't overlook the warning signs as they may cause more damage to the unit and even yourself. Prolong its useful life and increase its efficiency by hiring a professional to conduct regular tune-ups and proper handling. 

You might also want to check out these articles to help you with other related issues.

Mini Split Liquid Line Freezing Or Frosting Over – What To Do?

How To Clean A Ductless Mini Split Air Conditioner?

New Construction Mini Split Vs. HVAC: Which To Choose?

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