Most rehabbers will replace an AC unit that’s more than 10 years old, even if it’s working. This is because most quality rehabbers want to provide the end buyer with at least 5 years of maintenance free living.
The cost to replace a typical AC unit on a 3/2 house is approximately $3,000. If duct work is required or the AC handler needs to be replaced or repaired, the cost could easily reach $6,000.