4 Reasons Why Your Air Conditioner is Blowing Smoke

An air conditioner works by blowing cool air into a room. When in good working condition, the air is always odorless and transparent. However, when you notice the AC blowing out smoke or a white mist, it could be a minor or severe problem that should be checked.

Below are some of the reasons why your air conditioner is blowing smoke:

1. Clogged Drain Hole

If you notice your air conditioner is blowing a white mist or odorless white smoke, the problem could be a clogged drain hole. This is true, especially if the smoke blowing out is odorless. Excess water is stored in the heater box if the drain hole is clogged. The excess water can be reheated and find its way back through the AC vents in the form of mist, which looks like smoke.

While there is no cause for alarm, in this case, you should get a professional to clear the drain hole, so that excess water escapes. This problem is usually in older air conditioners. Newer air conditioners collect excess water in a pan, which is then reused to keep the AC cooler.

2. Higher Home Humidity

A white fog is formed when cold air comes into contact with warm air. The result is evident if the warmer air has higher humidity than the cold air. If your air conditioner blows cold air into your home with warmer and humid air, you’ll see it as smoke coming out of the vents.


A good example is when you see your breath when you go out on a cold day. Most of the time, there is no cause for alarm. However, if this keeps happening, check your AC filter and run the AC at a faster speed to cool your home faster.

3. AC Overheating

If the smoke from the AC vents is darker and has a strange smell, you have a more serious issue than a clogged drained hole or higher humidity. An overheating air conditioner can cause it to blow smoke, trip the circuit breaker, and stop the system from running.

Here are a couple of reasons why your air conditioner is overheating:

  • Dirty Air Filter – In air conditioners, air filters remove dirt and debris before it goes into your home. If the air filter is dirty and clogged, the AC runs harder and longer to force the air through the filters. This overheats the AC and can also break it down over time. The solution is to change the filter and restore normal airflow.
  • Low Refrigerant – If you have leaks in your system, the refrigerant will slowly leak out. If the refrigerant is too low, the air conditioner will constantly run and eventually overheat. Signs of low refrigerant include your home not being cooled quicker, AC having a hard time cooling your home on very hot days, and the outside unit is covered with ice on cold days.
  • Dirty Condenser coils – Condenser coils are filled with refrigerant that carries heat to the outside unit of your AC. If they are dirty, they can neither absorb nor release heat to the outside. This will cause your AC system to blow warm air until it overheats because the thermostat temperature is not met.

If you notice any signs of an overheating AC, shut down the unit and contact a professional for help.

Dirty Clogged Air Conditioner Filter

4. Electrical AC Failure

If you notice a burning smell and smoke, an electrical issue could be the cause. Most of your AC’s wiring is coated with plastic. A short can cause the plastic coating to melt or burn, and the smoke produced is pumped into your home. If you notice any smoke or burn smell, shut off the AC and call a professional to handle it.