Should I repair or replace my hvac repair north salem? Itís a common question, and you need to weigh several factors to make the decision. One of the most significant factors is the lifespan of your unit. A full AC or heating system replacement can be costly. Therefore, youíll want to consider if your old system is on its last breath before having it replaced. In many circumstances, you can have your AC system or furnace repaired to enable it to run effectively.