My rheem heating and cooling unit is set on heat, is running constantly, but the indoor temp is not increasing.I have it set on 73 and the indoor temp is 70. It has been running like this for the past 8hrs without any progress. What could be the issue?

Is it,, gas,electric, oil?, any and all extra info might help us help you

It is electric. The room temp is 70 degrees F. I set the heat on 72 degrees F. The unit is constantly running, but the room temp is not increasing. If I switch it to emergency heat, then the room temp will increase. There are two symbols showing on the screen: a fan on the left and some unrecognizable symbol blinking on the right. I can not find any information about what these symbols mean.