Electric fans will not operate properly

fan switch itself is bad,is under fans electeral hook up,this is where the fans hook under bottom of fan shroud.

Papa, Thanks for the quick reply. but there is no swtich located under the fan shroud of this modle. The fan relays are located in a fuse box located on the top of the passenger side fender well near the fire wall. I have checked both relay according to the service manuals instructions. plus I also manualy tripped both relays with a 12V source to check the fan curcuits and both fans worked fine. The problem seems to be that the signal that is needed to turn "ON" the relays themseves is not happening. Again I have checked the primary curcuit all the way back to the computer itself and everything is fine. I even replaced the temp sending unit just to rule it out. would you have any other suggestions?

The problem was solved. After performing a overheat test (installed carboard in "DIRECTLY" in front of the radiator) then mounted a mechanical temp gauge. Took the car for a spirited drive to heat it up fast and then brought it home and watched the temp gauge and the fan cyle action. the primary fan would turn on at 210 F then the secondary would turn on at 230 F. With the carboard in front of the radiator and the fans running full the gauge sat at 230 and the engine never even sputtered,knocked or choked once. once the carboard was removed the engine cooled down very quickly. once the gauge hit 210 F the secondary shut off then at 190 the primary shut down. the primary would cyle back on at 210. Knowing that with nothing blocking the radiator the engine would not reach 230 and for that reason is why I never saw the secondary cycle. So for you guys with roadmasters that DO NOT have a trailer tow package that is the deal on the fan cycling.