The belt should slip right into place. If it seems to be too tight or difficult to set in place, it may be necessary to adjust the motor mount to provide more slack. Then you can re-tighten the tension once the belt is in place. Check the manufacturer’s specifications for proper tension—in most cases, the belt should deflect about an inch when you press down on it.
PickHVAC Tips: First, see the PickHVAC tip above about sizing a central air conditioner. It applies to heat pumps just as much. Secondly, Even if the line set for the new heat pump is the correct size, we recommend replacing the set or at least the fittings. Old lines and fittings are a major source of leaks. When refrigerant leaks out, the heat pump efficiency suffers. Eventually, the unit stops providing heating and air conditioning, and it might break down.
In addition to the information below, see these two articles for the general care and maintenance of your air conditioner: Preparing Your Air Conditioner for Summer and How to Replace Furnace & AC Filters. Most noteworthy, you should replace the filters at least twice a year, before the heating and cooling seasons. For information on furnace problems, please see Furnace Not Working.