Your home's cooling system works hard. If you live in a warmer part of the country, your air conditioner might be in operation every single day. Even when its use is seasonal, that use can be heavy. It's no doubt alarming when your AC starts producing smoke that wafts through its vents and into your home, but is this a sign that you've been using it too much and catastrophic failure is imminent?
If what looks like smoke starts drifting out of the unit (either via the wall-mounted section of a split system air conditioner, or the wall vents of a ducted system), turn the unit off immediately. Now, inhale. This might seem like a strange instruction, but it's important to determine whether you can smell smoke. Your home's fire alarms may be triggered too. If your alarms remain silent, and you can't smell smoke, what you might be seeing is steam.
Steam is preferable to when an AC unit produces smoke, but steam isn't ideal either. The explanation is quite simple though, and you need to think about the warm air that is being drawn into the unit's outdoor component. Upon its introduction to your AC unit, this warm air is rapidly cooled, creating condensation. When passing through the unit's condenser, or heat exchanger, the moisture produced by condensation can be heated or vaporized. This water vapor can then enter your home as steam, which can have the density of fog, making it look like smoke.
This problem is often caused by moisture lingering in parts of the unit where it should not. The unit's condensate drain line (which is located on the outside section of the unit) should be expelling excess moisture in a slow, steady drip, which prevents the accumulation of moisture inside the unit. A clogged condensate drain line can be the culprit for your fake smoke problem. Have the unit serviced, since if the condensate line is clogged, then other parts of the unit are likely in need of maintenance. But what if it's not in fact steam that the unit is producing? What if you can smell smoke?
An AC unit that allows smoke to waft through its vents is dangerous. You must immediately deactivate it, and arrange urgent home cooling system repair. It's unlikely that the unit is actively on fire, yet continued use of your AC increases this risk. A loose component inside the unit (such as its belt-driven fan) can be creating significant friction, and producing smoke. You need professional AC repair so that the faulty component can be quickly identified and replaced.
Steam or smoke being produced by an AC isn't an encouraging sign, and needs to be investigated and repaired. For more information on home AC repair, contact an HVAC technician.