Because we live in a desert, Arizona’s temperatures drop dramatically over night and in the early mornings. This may cause frost, or ice to develop on the outside coils of your system causing cold air to blow into your home when your heater turns on. Don’t be alarmed, this is a normal process called a “Defrost Cycle”. It may take up to 20 minutes for the cycle to complete, causing cold air to blow into the home during this period. Once the cycle has completed itself, your system will return to it’s normal operation. If this problem is persistent and not allowing your home to heat up for more than 6 hours at night, you will require service on your system. Please feel free to contact us 24 hours a day to discuss your concerns. You comfort is our main concern.