0 Barry Roswell, GA on Feb 02, 2011 Like Clip should you change the ac when you change the heater 2 Comments Darby C Flowery Branch, GA If you are putting back the same brand, then you should be O.K.. Is the AC newer then the furnace? Bullseye Properties, LLC. Cumming, GA both units have to be copatable, if so, you do not have to. NOTE: You can drag and drop your photos to reorder them Required Comment Saving...