I changed out the resistor and now it has all speeds except High. On high it spins like it's on low

 

Did "HI" speed work before you replaced the resistor?

This sounds like a switch or wiring problem. You will need to trace the wiring from the switch to the blower motor. The switch provides the ground for the "HI" speed.

"HI" speed does not use the blower motor resistor.

 

Thanks. That makes sense.

 

when i first got my 94 the switch was burned up along with resistor

 

Hello fellow Toyota owners.
I have one for you, I've owned my 91 4runner since new, I've changed my 5 position fan switch at least 5 times.
I always lose the medium #2 position that is up next to High position. The other positions never fail.
any suggestion?

 

Like the DR. Says, stop doing that.

Have you inspected the resistor, the wire, or wire connector?

 

Inspection shows heat at the plugin for the switch.
the resistor checks good.
When the new Switch is installed, all four speeds work for several month and then it always loses #2 medium next to the fast position.
I'm considering installing a PWM pulse width modulation DC speed controller rated at 30 Amps.
There are many on ebay and amazon.
To do this right, I probably need to utilize the existing switch to power up the PWM controller with a SSR solid state relay.
The SSR would be fed from plus 12vdc
This would give infinite speed control. Some times when it's not too hot, the existing low speed is too fast.
I know the existing wiring shows a second trace of low speed operation paralleled at all speed settings.
I Guess this is to eliminate a freeze up from no fan running if you lose a fan position.
Any one have a electrical schematic of this circuit for a 1991 4runner?

 

This is for a 93 pickup, I believe a 91 shares the same schematic:

http://personal.utulsa.edu/~nathan-b...g/25heater.pdf

 

If you have heat at the switch connector, that would indicate some sort of resistance in the connector that shouldn't be there. This could be caused by corrosion, lose wire(s), or poor connector pin fitment between both halves of the connector.

Does the connector ever look burnt or corroded?

Here is the schematic for a 1993 4Runner. The system is set up the same as on your 4Runner. A few of the wiring colors shown in this diagram may be different than what you have.

 

Haha, you beat me to it by a minute, but you found the simpler diagram!

 

Heat damaged plug should be changed. Burnt plastic/rubber turns to carbon, carbon conducts electrical flow