Heat pumps can ice-up during the winter time. And it is normal for the entire coil to be covered in a white frost, even light ice, during certain weather conditions. But it is not normal for the entire unit to be encased in ice; including the top of the unit and the insides of the coil for an extended period of time. This indicates a problem and should be addressed quickly to save energy and avoid serious damage to the equipment. Heat pumps will naturally ice-up in the winter but will periodically go into a defrost cycle to de-ice the coils. This keeps the unit running efficiently. If the coils are blocked by ice, proper heat transfer between the refrigerant and the outside air cannot occur. The unit pictured left, was iced-up so badly, it damaged the fan blades, crushed the outdoor coils; causing the refrigerant to leak out and ruined the compressor - a complete loss. On a call for defrost, the reversing valve is energized, switching the system into the air conditioning mode.

That is right - Air Conditioning. The outdoor evaporator becomes the condenser but at the same time the outdoor fan shuts off. how does air conditioner work in winterThis allows the high pressure refrigerant circulating through the outdoor coil to get very warm, melting the ice.portable a/c units for car At the same, the second stage heat (the back-up heat) is energized to offset or temper the cold air now blowing out the vents. ac units direct.comWhen a sensor or thermostat in the outdoor unit reaches a certain temperature and/or a certain amount of time goes by, the system goes back to normal heating mode. At this time a cloud of water vapor can usually be seen rising out of the outdoor unit and a "whoosh" sound can be heard as the refrigerant reverses direction.

The entire process usually takes between 2 to 10 minutes depending on conditions. Different heat pumps have different ways of determining when to go into defrost. Some (older models) use mechanical timers in conjunction with a defrost thermostat. If the thermostat is cold enough and enough time goes by, the unit will go into the defrost mode, whether it's iced-up or not. When the thermostat heats up to a certain temperature, defrost is terminated. Hopefully at this time, much of the frost has melted off. Most of the newer equipment today uses solid-state control modules with temperature sensors. Even more sophisticated is the Demand Defrost system which makes calculations based on the outside air, the refrigerant temperature in the coil, and run time. This is the most efficient way to defrost. If a heat pump is severely iced-up during winter use, it's possible that it's not defrosting, but there are many other causes. Bad defrost control or timer Bad defrost thermostat or sensor

Bad reversing valve solenoid coil Bad outdoor fan motor Outdoor coil blocked - possibly with leaves or snow drift Unit sunk in ground - nowhere for ice to melt and drain off Leaking gutter dripping water onto top of unit Freezing rain - causes top of unit to freeze over - once this happens the rest of the unit will also freeze over If the top of the heat pump is covered in ice, turn it off and remove the ice. If a gutter is dripping on the heat pump, repair the gutter. Keep snow and leaves away from the heat pump including underneath it. If the heat pump has settled into the ground, it must be elevated - usually on blocks or special feet. (Should be done by a technician) With the outdoor unit of, (you can set your thermostat to emergency heat), ice can be removed with a garden hose. If the heat pump ices-up again, it is time to schedule a service call. Important: Whatever you do, please, never pick the ice off with a sharp object.

The refrigerant coils and fins can be damaged very easily.Even during a scorching Kansas summer, when temperatures outside soar, ice can build up on or inside your air conditioner. This can lead to big problems, so it’s important to know why ice can form on an AC unit and how to prevent your air conditioner from freezing up. First things first: If you have ice on your air conditioner, shut the unit off now to allow it to defrost while you read on to determine whether you need to call a professional for service. If your air conditioner freezes up, it’s either because something is preventing heat from transferring from your house to the Freon, or something is causing the evaporator coils to get too cold. Air conditioners work by transferring heat through a refrigerant called Freon. The evaporator coil expands the Freon, which causes the coil to cool quickly. Air is blown over the cold coils and distributed through your home’s duct work to cool the air in your house.

The refrigerant inside the coils absorb the heat from the air, then moves outside your home to the compressor. The compressor causes the Freon to release the heat from your home into the outside air, and they cycle starts again. Cause: Low refrigerant levelIf your refrigerant is low, you have a leak. This causes the Freon to expand too much in the air conditioner’s evaporator coil, lowering the temperature below freezing and causing ice to form.Solution: Have a qualified HVAC technician repair the leak and recharge the coolant.Prevention: Have your air conditioner inspected and serviced every spring to catch potential problems and make sure it has the right amount of Freon. Cause: Dirty evaporator coilA dirty evaporator coil can cause ice to form on your air conditioner because it restricts airflow through the unit. A dirty coil can also make the AC unit use more electricity while producing less cool air, and cause significant damage to the compressor. Solution: To prevent your cooling system from breaking down completely, shut the unit off until the coil is cleaned or replaced by a professional.

Prevention: Clean the evaporator coil regularly. Cause: Restricted Airflow through the AC unitIn order to function properly, air conditioners rely on air flowing through the system. Too little airflow reduces the temperature, causing the AC unit to freeze up. Airflow can be restricted by dirty air filters, closed vents, or by clogs or leaks in the ductwork.Solution: Depending on what’s restricting the airflow, you may need to change your air filter, clean your ductwork or repair your air ducts.Prevention: Change the air filter once a month during heavy-use times like summer, and consider having your ductwork sealed. Cause: Outside temperature is too coldAir conditioners weren’t designed to be used when the outdoor temperature is below 62 degrees Farenheit. This isn’t usually an issue here in Wichita, except during the late spring and early fall, when temperatures can get into the 70s and 80s during the day but drop down into the 50s overnight.Solution: Turn off the AC unit to allow it to thaw.

Prevention: Turn off the air conditioner at night when the temperature is predicted to be in the low 60s or lower. Cause: Mechanical failureBroken valves, a damaged blower fan or fan motor, kinked refrigerant lines, or a blocked drain can all cause your central cooling system to freeze up. Solution: Have a licensed HVAC professional inspect and repair the unit.Prevention: Regular maintenance of your heating and cooling systems, generally in spring and fall, will ensure all parts are working properly. Ice inside your AC unit can’t be seen as easily, but it can cause serious damage so it requires service immediately. In the humid climate here in the Midwest, it’s common for air conditioners to drip water. But, if a lot of water is dripping inside the unit, that’s a sign of trouble. A full drip pan can indicate melted ice inside the AC system. Another red flag is the sound of ice chunks falling, like when your refrigerator defrosts. If you notice either of these signs, shut off the unit and call an air conditioning technician right away.