The heating message should absolutely work in an identifiable way plus when failing to do so, it is evident a problem is occurring. This happened during the last summer when our heat pump was frozen. I panicked because I did not know this was something that could occur. It was quite evident there was a problem. This type of instance would be expected for winter weather but it seems unusual for ice to be appearing during the middle of a hot and humid summer season. I contacted the local heating, ventilation and AC specialist in order to have them check it out. The specialist arrived about 2 hours after I called plus had the problem diagnosed in a matter of minutes. The thermostat setting was entirely too low. The experts proposed not directly setting the temperature lower than 75 degrees. If you do this, there can be a cause for potential freezing on the indoor coils. The heating, ventilation and AC ductwork can sweat as well which causes excessive mildew + mold. Naturally occurring cold weather causes a lot of ice to form near the heat pump and this can be quite an alarm when it occurs during summer seasonal weather. Several causes can happen and there could be a problem with a faulty expansion valve. It could be a disfigured indoor coil and there could even be a jam shelter. Problems with the thermostat will also cause the heat pump to freeze so there is no way to know without calling a heating and AC repair company.