Ok ; if I understand your explanation of the issue ; your furnace blower motor is running .
Do you have propane to the cook top ?
Have you placed any carpets in the coach that might be restricting air flow through the registers ?
Any air flow restriction ( outlet registers , or return air ) can effect an RV furnace's operation .
The air flow must be unrestricted for proper " sail switch " operation.
Do you have the owners manual for the furnace (s) ?
Manual has a good troubleshooting section .