Don’t panic, your fan isn’t burning up and it’s not smoke coming from your heat pump – it’s steam. You can breathe a sigh of relief knowing that if steam is rising from your heat pump, it means your system is doing its job. During the heating season, your heat pump will develop frost on the outdoor coils in colder temperatures. When this happens, the heat pump’s controls sense this frost and enter “Defrost Mode” to melt the frost from the coils.
Here’s a more detailed explanation: A normal AC system is designed to absorb heat from inside your home, and then dissipate it to the outdoors. The heat pump system does the same thing in the cooling season, but the advantage of a heat pump is that it can absorb heat from outside (yes, heat) during heating season and dissipate it into your home. Because of the outdoor air temperatures being cooler, the moisture in the air will freeze on the outdoor coil. Heat pump systems have controls called “Defrost Control,” which will check every so often to see if the coil needs defrosting. (Just like your frost-free freezer/refrigerator.) If so, the heat pump will do three things. 1.) Turn off the outdoor fan motor, 2.) enter the cooling mode, and 3) electric heat is turned on. The heat pump will stay in defrost until the controls have sensed the frost/ice has melted. Upon the completion of defrost cycle, the unit will return to heating mode, turn off the electric heat and turn the outdoor fan back on. Often steam or fog will be seen coming out of the outdoor unit at the end of defrost cycle.
You also may experience a strange smell inside your home during defrost. This is usually dust on the electric heating elements inside your indoor unit. The steam and strange smell are normal heat pump system functions and you shouldn’t be concerned. The defrost cycle may happen more often during colder or wet weather.
Never defrosting, prolonged defrosting, extreme frost build up and extreme utilities may be signs of system problems. If you’re in need of AC repair or maintenance, our professional team at Champion AC is here to help. Call us today with any questions you may have about your HVAC or to receive a free estimate.
Ben is a retired Combat Controller with the United States Air Force. He started Champion AC in 2007. Ben is originally from the Mississippi Gulf Coast. He is happily married and an avid fan of the San Antonio Spurs and New Orleans Saints.