2006 a6 heater core flush tips
 

Alright so the wife has a 2006 a6. 190k. Heat isnt working good up here in the midwest. So i tryed to flush it with clr and hot water from the washer hookup. Any vehical i have done this on only have i inlet and 1 outlet. So i flushed thoes two on the passenger side and no gunk came out. But it appears their are two on the passanger side of firewall that connect to 2 cylinodes then back down to one hose and go somewhere. And another one on the drivers side next to the brake booster. Is thair any forum that shows how i flush this. Im assumeing the passanger side two hoses are eather the inlet or outlet. And the one on the drivers side is the opposite. Help. It was -17 yesturday. Fyi this has the battery in the trunk these years and cant find any videos.