96 caravan heater control module

i have a problem, if the heater control module won't take caliberation, how
can i find out what diagnostic procedures i need to perform to got it
working. i have tried two different control heads from a salvage yard and
nether have even started much less finished a caliberation. the dealership
told me i needed a new one,for $400, my old one almost caliberates but at
the end, both wiper and intermitent flash together.and blows hot air out
of drivers side vents and cold out pass side.