How to Wire an Outside AC Condenser | Hunker Oct 21, 2017How an Air Conditioning Condenser Is Wired. The installer or electrician must install two sets of wires when connecting the condenser. Both are connected to the same contactor relay, located inside the condensing unit. One set of wires provides high-voltage 240-volt current that powers the fan and compressor unit,..Author: Bryan Trandem How do i wire my a/c condensor to work with my furnace. I Nov 29, 2009These are the only control wires between the the a/c unit and the furnace. The 240v circuit for the a/c comes directly from the panel to the outside disconnect then to the a/c unit. You will need a minimum of 4 wires to the tstat in the home, if they are not already in place.