The unit is an arcoair not sure how old it is, it was here when we bought the house 5 yrs ago. We had fan replaced last year and this year it seems to be blowing cold air for longer than usual. The thermostat is set at 72 the temp is dropping to around 63 while the unit is running and it is blowing cold air for apx 15 minutes or so, then the aux heat kicks on and the house finally starts warming. Is this normal for a heat pump? Doesn't seem like it did this before.

I believe it is time for you to have the outside unit looked at by having a On Site service call to figure out what the problem is.