the little electrical thing with wire coils on it that mounts with one screw thru the top of the heater box  , the repair manual calls it this , but what does it do and can my zuki live with out it ?

A "registor"?  Maybe a resistor?  There should be a resistor used to control the blower fan speeds mounted on the the blower housing, and yes, you could live without it.

It is the resistor pack, the resistors lower the motor speed. You can live without it, but make sure the wires are properly connected to have a single speed fan, always on high.

I would clean the heater core.

 So if I currently just have the 2 highest speeds, could it be the resistor or the switch? Thank you,

Kj

It would be the resistor pack more than likely. Also I have seen many a resistor pack fail in such a fashion that you have the selector lever on high but are actually at a lower speed. Resistors fail in one of two ways, they either increase resistance or open, and usually increase resistance untill they overheat, burnout and then open.

I'd say it's a toss-up - I've seen both defective switches and resistors

i threw that "registor" and the related harness away before i knew what i was doing. i thought it had something to do with the a/c stuff i was removing.
i now only have a high speed fan(or off, of course).
sounds like your unit went bad. should be able to check switch function at that connector?





i may try a resistor pot for regaining control- could work?

i may try a resistor pot for regaining control- could work?

If you could find the right resistor pot, it would, but the chances of that happening are slim to nil - you'd need a low resistance, high wattage wire wound potentiometer - what's more commonly known as a rheostat, and finding a rheostat with a low enough resistance won't be easy, or cheap.

Go get a switch & resistor from the junk yard - it'll be easier & cheaper.