where is the heater control valve located on the 1997 lincoln mark viii

my 97 lincoln mark viii only blows cold when the heater is turned on. before i have the blend valve replaced that requires fully removing the dashboard,i want to check the heater control valve if there is one.this ia what the chilton manual suggests though the manual cosn't show where it is.could you tell me if there is on on the mark viii and if so where is it located. thanks,rick