1980 Datsun 720. Anyone ever had this issue? Off, 1, and 2 work just fine, and it blows hot, but highest speed stopped working a few months ago. I've taken apart the assembly and cleaned the contacts but still no luck.

what gives?

thanks,
Justin

Holy crap. I honestly can't even think of what would cause that one

If you cleaned the contacts and whatnot, I assume you would have noticed if any of the linkage was broken...... ummm.... yeah not sure.

yeah i'm stumped too. one thing i did notice is that the fuse box labeled the heater with a 20A fuse. when i went to look at it, there isn't a fuse in that location. so i thought i had the solution but then that location doesn't actually receive a fuse. the metal prongs that hold it in place are missing. the plastic housing is there, just like the rest of the fuse locations, but the fuse just slides in and out. but even if that were it, why would the other speeds work on not the highest one?

where could i track down a new switch assembly?

You can track new ones down in junkyards and in classified sections on craigslist, ebay, and obviously forums

the switch is easy to test just put your spark chaser on ohms and check for continuity through the various switch positions, otherwise....

actually this is a fairly common problem with industrial fans and what not, its a number of possibilities, one the blower could have mutiple windings for each of the fans speeds in which case the high speed winding is burned out, another possibility is it uses what are called shunts, or a metal bar shoved in various stages of the windings to change rotation angle. or more than likely its resistive (burned resistor or failed winding), there are also capacitor style dealies but thats mostly with AC same with the shunt wound. all things lead to the most simple of fixes replace the blower.

Thanks for the info. I might replace the blower. Just not sure I want to spend the dough when speeds 1 and 2 are sufficient.