Replacing both the outdoor and indoor HVAC units is a must. Systems that are matched perform better and more efficiently than systems that are not matched. In fact a unit that is not matched is not living up to it’s full efficiency rating since these ratings are based on matched systems. This could cost you more money on your monthly utility bills. Also, some companies will not extend a full warranty to systems that are not matched. In order to ensure you have an HVAC system that is performing at it’s optimum efficiency level, you should replace both units.
Read more: Do I Need to Replace My Indoor and Outdoor HVAC Unit At The Same Time?