Strange problem

Asking for a friend who has a 1998 van. Whenever the 12 volt supply is switched on at the control panel the fan on the heater runs for a couple of seconds, pauses for a few seconds and then does it again and again.
I don't even know where to start looking for a solution. Has anyone ever come across something like this? 

Second problem, the pipe from the pump on the toilet flush system has come off, is there an easy way to refix it or is it just a struggle when your hand down the hole where to roll holder sits?

Thanks in advance for any suggestions.

Hi, the pipe on the toilet flush in our executive is just a push on fit , not very tight but seems to stay in place , could check the outlet part to the bowl is not blocking up, as for the fan on off poss check all plugs and wires are secure, and any sensors are clean, sorry but best i can do im affraid.

Thanks, good tip about the outlet pipe, a blockage there could be why it blew off in the first place.