If the air temperature near the appliance is below the dew point, this causes water vapor to form in the air and condense into water droplets, thus causing the fog or smoke. A dirty air filter or low fan speed may aggravate the condition.
Nothing to be alarmed at: harmless, cooler water vapor condensate is hitting warm, humid room air, creating a cool steam, much like cool-air humidifiers.
When it senses frozen coils, the heat pump reverses its cycle to work as an air conditioner for a short duration. The heat pump warms up and releases heat to melt the frost build-up. The steam that comes out of the heat pump on cold winter days is a result of melted ice being released into the air during defrosting.
Fog or smoke coming out the air vents is caused by cold dry air coming in contact with warmer, more moist air near the air conditioner. If the air temperature near the unit is below Dew Point, this causes water vapor to form in the air and condense into water droplets causing the fog or smoke. No worries!
The air conditioner's cooling cycle includes pulling in warm air that is then cooled. As a result of this process, condensation is produced. When moisture builds up in the heater box, it may eventually turn into vapor and get released with the cooled air, so you see white smoke coming from the air conditioner vents.
Worried about that fog or the mist you see coming from your AC? Don't worry—it usually doesn't mean there's something wrong with your air conditioner. The mist is just condensed water vapor that forms when cold, dry air comes into contact with humid, warm air (we'll explain this in more detail later on).
Without prompt attention, excess condensation could overwhelm your air conditioner's drainage system, causing damage within your home. This damage can range from high humidity levels that lead to mold and mildew proliferation and spots, to structural damage from drainage water that accumulates and puddles.
It is common for the white fog to form when cold air collides with warm air (that's highly humid). This can be likened to when you go out on a cold day, and your breath is visible. Warm, moist air hits the cool, dry air, causing condensation or water droplets to form. This can be seen as a white smoke or fog.
That “smoke” actually is water vapor that forms when really cold air moves over relatively warmer water and the thin boundary layer of warm air just above the surface. When the evaporating water rises, the cold air can only hold so much moisture, forcing the liquid to condense into fog.
Sometimes it can be caused by water accumulating in the vent system after it condenses. That water can wind up at the bottom of a vent, and when you turn on the blower motor, it can cause what looks like steam or vapor to come out of the vents.
If you notice a change in the airflow of your HVAC system, then you should look into calling a professional. They can come out and test your equipment to determine how strong the airflow is. How strong should air come out of vents? The recommended airflow for each room is typically 50 cubic feet per minute.
One of the most obvious signs is a puddle of water in your AC's drain pan, which proves the water isn't draining as it should. Other signs include: Standing water near your air conditioner's condenser unit. A moldy smell around the drain or from your system's vents and registers.
Condensation in AC vents is most common during the spring and summer and occurs when moisture-saturated air makes contact with a colder surface. The cold surface cools the water vapor, causing it to condense into drops that collect on the surface of vents.
Check your filters and replace them if necessary.
If your filter is dirty or clogged, it may be the reason why your AC isn't blowing cold air. Dirty filters can cause a restriction in the airflow. To check if this is the case, remove the filter and inspect it for dirt.
Here's how long some of the most common types of AC last:
Window Unit AC — 10 years. Portable AC — 5-10 years. Residential single whole-home AC unit — 15 years. Central air-source heat pumps — 15 years (and up to 20–25 years if well-maintained and in a well insulated home)
If you don't have enough refrigerant, it won't be able to cool the air. But if you have too much, the pressure will be too high for the refrigerant to boil or for the compressor to work. Which means the system won't cool at all, and you'll still be left with hot air.
Low refrigerant levels from a hidden leak or failure to top off refrigerant may lead to cooling system issues. Besides inefficient cooling, low refrigerant levels can lead to frozen evaporator coil issues. When the ice melts, the excess condensation may lead to a water leak.
To unclog an AC drain line, turn off the power to the unit. Locate the drain line and use a wet/dry vacuum to suck out the clog. Flush the line with water using a garden hose or cup of water. Check and clean the drain pan under the indoor unit.
If the air temperature near the appliance is below the dew point, this causes water vapor to form in the air and condense into water droplets, thus causing the fog or smoke. A dirty air filter or low fan speed may aggravate the condition.
It is the humidity of the warm air suddenly becoming condensed by contact with the warm air, causing water droplets that are seen as smoke or fog. A common cause for this is that your air conditioner is not getting sufficient airflow through the system.
If the moisture higher and condensed it is called as mist or dew or rain etc. As the A.C machines cools the air, the moisture is also cooled and moisture is in the form of steam or vapor and it condenses and changes to water and the A.C machines drips it away. It's not harmful, it's normal.