As mentioned... do not run this unit until it is checked out
Depending on its age... you may be in for a new system... Not trying to spend your $$$... rather prepare you for what may (or may not) happen.
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!