I do service, not much replacement-customer needs new compressor on 23 yr old 4 ton, GE ht pump (maybe 10 seer). Air handler in good condition, in tight closet, finished basement. It worked fine for 23 years. Rather than replace air handler (difficult), would it be ok to use 13 seer 4 ton OD R22 Bryant, exist. refrig lines (size ok), and change out coil and txv in air handler? The new coil would fit, with some sheet metal baffles, air flow would be very similar.
I could put a fan time delay in, adjust the airflow up if needed. Is there anything I would loose other than indoor solid state board, and tested ratings? The indoor coil would be the 4 ton coil matched for this system, just the one from replacement parts dept. rather than new equip sales..they would like to sell me the whole air handler.