If you have a Heat Pump, you have a low charge, you'll notice your indoor air will be luke warm at best, but switch thermostat over to Emergency Heat. This will activate heating elements inside of your furnice, will provide temporary heat until you can get service out to charge unit. Also check your Air Filter, if clogged will cause lines to outside unit from Air Handler(Furnice) to become incased in ice.Re member a heat pump only heats efficently up to 34 degrees. After that you should switch over to Emergency Heat, it always amazed me that they install those unitd in the mid west.
