1998 Ford Mondeo heater not working

when you turn the dail switch from hot to cold can you feel any resistance if not then the cable has come off or is broken but also check the pipes under the bonnet as the car warms up feel if they are getting warm these are he ones that pass through the bulk head behind the engine if these pipes are not getting hot then the problem is a air lock in the system check what i have said first and see how you go