Monte,
Here is how your cooling fan works. It is a hydraulic motor that is drive by the same pump that powers your power steering system. The hydraulic pressure is controlled by a wax valve located in the coolant flow as it leaves the radiator.
Since you did not mention a power steering issue, we will assume the hydraulic system is operating normally. That leaves the fan motor or wax valve as the problem. However, the most common problem that causes a fan operation problem on your model coach is a low coolant level. The wax valve does not operate properly unless it is emerged in coolant, so a low coolant level can cause an inoperative fan. If you are certain that your coolant is full, since the fan motor and wax valve are both expensive parts, you should probably get the system diagnosed by an experienced mechanic before you start throwing parts at it.
Gerald