rollypolly

Hi Resale Home owners, I recently bought a resale 5 room flat. The sellers has aircon installed in their master and two other bedrooms 'a few years ago' however aircon units though workable and seemingly in good condition, flaps are damaged in one room. Will you recommend to retrunk and change all the units? I have heard mixed reviews that it is good to retrunk and change everything out if you're going to be staying there for the next 10 years. I don't mind spending the money if necessary, but would like to gather opinion on whether it is necessary to change the trunking and all units. Does the trunking disintegrate over time? If yes, how often? Or is it advisable to change only the damaged unit since the rest are in seemingly good condition? Also for rewiring, is it necessary to rewire the whole house? Our resale unit is 23 years old and we are going to be the 3rd owner of the house. Is partial rewiring possible? Thanks! :-)