Q- Can I just change out my old defective heat Pump (condenser) with a new one and save my old air handler

A- Most county municipalities won’t allow you to miss match equipment. It is a code violation. Each system must have an ARI Reference #Rating or ARHI Reference # (American Refrigeration Institute or American Refrigerant Heating Institute). This reference number insures the system is capable of delivering the rated Seer from the factory. Studies have shown that miss matching equipment can result in lower Seer efficiency and higher power bills.