What To Do When Your HVAC Unit Ices Over In Wintry Weather

Having a full HVAC system can be a godsend amid more extreme seasons. Whether you need to crank the heat during winter, efficiently blast your A/C during summer, or just filter your air quality, keeping regulated ambient conditions is one of the best ways to stay comfortable. However, an air conditioning system needs to be prepared for winter regardless of whether it's installed in one room or if it's an outdoor unit that feeds central vents. If you don't cover or remove your air conditioner (without blocking the condensing unit pump if it powers your heater), the refrigerant inside can fall below freezing temperatures, leading to ice forming. Too much winter build-up can waste energy, but also lead to hundreds of dollars worth of damage. So, how do you fix a frozen A/C unit?

Conventional HVAC heat pumps have a defrosting cycle which can run on 30-, 60-, or 90-minute intervals to warm the outdoor components, but this inadvertently cools indoor spaces — and may not be strong enough to clear the problem. Trying to scrape ice may lead to damage, as might solutions like pouring hot water on the unit. There are broad steps one can take to prevent HVAC systems from freezing over, such as removing outdoor debris or snowfall and trimming back foliage to promote better air flow, but winter conditions are likely just exacerbating issues that already require maintenance. You may have no choice but to turn off your thermostat and wait a few hours for the unit to defrost in order to fix things once your HVAC unit thaws.

Even if you keep your residential heat pump charged, that HVAC unit and your air conditioner should be replaced every 10 years or so. If the unit is still within this window and you notice abnormal ice build-up even outside of wintertime, you can troubleshoot a few issues yourself. The root causes of a frozen HVAC unit can include dirty air filters (check the return ducts and grills for central A/C, or the grill facing inside for a single-room unit), debris build-up in the drainage system, low or leaking refrigerant levels that cause the unit to work harder for weaker results, faulty wiring, or inaccurate thermostats leading to improper usage windows.

Blockages due to outdoor debris build-up or dirty air filters are issues you should theoretically be able to handle by yourself, but anything more than day-to-day maintenance should be addressed by a professional technician to ensure your HVAC system is in tip-top shape before winter hits. Watch for symptoms of your A/C system freezing over: the unit running continuously with lesser results, a significant amount of water drainage or condensation build-up, visible ice on the refrigerant line or evaporator coil, or strange noises from the heating system. 

There are over 200,000 technicians who work on HVAC units in the United States alone, and they can check related issues with indoor heaters and air conditioning systems, or looking at the combustion of your high-efficiency furnace. It's worth keeping someone on speed dial so you that your home remains a comfortable place to hide throughout any icy winter.