Its been doing this for some time, sometimes it's for half a second, some times several seconds. Today I had to disconnect the batter???

 

I wonder if your ignition switch is that worn.

The contacts are not opening like they should be.

Might be full of dirt that conducts electric

Any other switched power staying on like the radio , Wipers ??

Then with Toyota`s interesting working repairs turn up all to often

 

To me this sounds like a resistor or relay problem for the blower. Does it happen only on one speed or all of them?

 

This sure sounds like a sticky heater relay. There is a test procedure for it: http://web.archive.org/web/201102052...g/25heater.pdf , but it only checks for continuity. You'd probably need a pretty good current through the contacts to replicate "stickiness" on the bench.

Unfortunately, it looks like the Toyota part is no longer available. https://parts.lakelandtoyota.com/sho...modelYear=1992 But it's just a 12v SPDT relay (and I'm not sure the double throw part is absolutely necessary), so you can probably find a universal version to fit. (Though the pin orientation doesn't look like the standard ones.)

 

Radio everything else shuts off.