My 91 b13 heater fan works on 1-3 but not 4 i have checked the fuses and swapped resistors from my buddys b13 that works on all 4 i cant seem to figure it out. Maybe the switch is bad?

replaced the blower motor switch. its on the bottom of the blower motor. just unplug it and two bolts.

alright thanks you know if its the plug that is a two pin plug?

there you go my friend
https://www.gspec.com/p-7326-fan-control-resistor.aspx

i replaced that already and it still doesnt work :(

hum.... thats a first . everyone elses it was that. has to be the control then

ya thats whats what im thinking since 1-3 work and 4 doesnt its backwards of what most people have problems with

i'll be tuned to your solution because mine does the same, all except 4. i haven't tried changing the blower resistor yet though.

mine works on 2 & 4 but not 1 & 3

Im going to try to mess around with it this week or weekend i will keep you posted

i have the same issue, 1-3 work but not 4. let us know when you find a solution.

should be that resistor for most of us that was the solution for me.

the blower resistor controls fan speeds 1-3, just uses up certain amounts of voltage so the blower gets less voltage causing the fan to spin slower. position 4 allows the full 12volts to go thru the blower motor. you may have an issue with the wire that is soldered to the bottom of the fan switch on the #4 position. sometimes the solder comes loose, you may be able to remove the climate control assy and re-solder the wire to the switch( if this is the problem) use a test light to see if you have power on both wires at the blower motor on #4 if you do i would start looking at the switch.

i have the same problem.. but 1-2-3 doesnt work, only 4

i have the same problem.. but 1-2-3 doesnt work, only 4

THEN YOU need to replace this tps://www.gspec.com/p-7326-fan-control-resistor.aspx you can also get it from autozone.

if only 4 works than its the resistor, if only 123 works and not 4 than its a switch

ok,,,mine works on 2 & 4 , but not 1 & 3

alright thank you guyz :biggthump

its the blower motor resistor ...two screws one plug...put it in your pocket and voila i would suggest getting a few of them....hehe