During the winter months when the outdoor temperature generally falls, the outdoor section of the air conditioner may start to form ice over the coil. This is a normal occurrence because the coil temperature is approximately zero degrees or below. Zero degrees; of course is freezing point for water that may be in the air as relative humidity.

When the unit goes into a de-ice mode, the following should occur in most units:

  • Indoor fan stops circulating air (excluding Room Air Conditioners)
  • The system switches back to cooling mode automatically
  • The compressor in the unit keeps running (humming noise)
  • The outdoor fan may run pending on the type of system
  • A temperature sensor or timer tells the system that defrost has been completed
  • Unit then switches back to the heating cycle automatically
  • The indoor fan will start up (fan may blow cold air initially)
  • When the unit goes into the de-ice mode, the unit should remain in the “ON” position. This will allow the operation to be completed quicker.
  • If the unit is turned “OFF”, the outdoor section may then defrost. As the function has been initiated, it may not start immediately, until the timer has cycled through. Some areas are more prone to lower outdoor temperatures than others are. For example: valleys are a lot colder than hills. All brands of units have a de-ice function, with some coping better than others in this situation.
  • When heating, it is also normal for water to come out of the outdoor unit, rather than the drain. Only the indoor unit is drained.
  • Please take this into consideration, as any service calls related directly to this function will not be covered by the warranty, and will thus be charged to the customer.