How do I know how much an air conditioner repair service or new equipment install should cost?

Get more than one bid (preferably three) unless the bill is not that high (you will end up paying more in trip charges/diagnostic charges than the original bid on a small bill). When getting the bids make sure that you are getting the same air conditioning equipment and service from each of the contractors. An example of not always getting the same service would be on an equipment system change out.  Some contractors replace your service disconnect as part of a unit change-out, while others don’t unless it is specified in their contract with you.