[PlazaGuy]

Does anyone know what this switch might be for? It's right above the radiator on the passenger side and next to a small locking door for the coolant reservoirs?

We had a 1990 and the switch is part of the heating system. I can't remember the name of the system, but there are two reservoirs behind the door by that switch. One feeds the front part of the heating system and the other feeds in the bedroom area. If you have no heat you can check those two little reservoirs by unscrewing the top and if they are low you take the tube that is in the picture insert into the reservoir, flip the switch and it pumps a 50/50 mixture of antifreeze and water from a larger reservoir that's located on the firewall in the engine compartment on the passenger side. Of course, you would have to had put that mixture in the larger reservoir for it to do that. My phone # is 913-220-9553 if you have questions you think I could answer.  Ed Perkins