You are able to do so as long as the tonnage stays the same and the same refrigerant is being used. However, you are not able to swap out a Goodman condenser with a MRCOOL condenser. MRCOOL cannot work with existing furnaces and coils; you would need to do a full system swap and get the MRCOOL air handler as well. Their air handler has an integrated coil inside as well as a blower motor, which requires a MRCOOL condenser to be matched with it.