What should i check for to make it blow on high again, this is how i got the truck so idk how the problem started

 

The blower switch connects through the blower resistor to the motor. On highest speed, it connects direct to the motor. Since yours works on at least one lower speed, the problem is probably not in the resistor, but in the switch itself.

Testing the switch will be easier if you use the schematic. Which will be easier to find if you know the year/model of your truck.

 

alright how do i test the switch tho

 

The blower resistor is a set of high-power resistors connected so that on low speed setting, the most resistance is in the circuit causing a low speed on the fan. Each higher speed selection from the switch bypasses a resistor which in turn lowers the resistance in the circuit resulting in higher blower speeds until you hit the top speed 3 or 4 depending on some things, where there is basically no resistance and the fan blows as hard as it can.

The resistor is located behind the "glove box", and is mounted to the firewall. It's a little awkward to reach but otherwise pretty easy. If it has issues, a simple visual inspection will reveal those: burnt resistor wires are easy to find there.

And, you'll need to pull the resistor to check your switch wiring since the switch connects to the resistor.

 

hmm interesting alright ill check it out tomorrow thanks

 

It's the resistor I bet. It will be easy to tell as the little coils will be visibly burnt up. Under $20 to replace from dealer.

:wabbit2:

 

Check the simple stuff first. Pull the switch out of the dash and look at all the contacts. Make sure they are clean. Mine failed because the contacts were dirty. After cleaning them the blower motor worked again. If the switch is good check the resistors.

 

alright ill check thos out to

 

well i took a look, and i could find the resisters but when i turn the fan on low i herd it click on then went to mid and no click dos this help in any way

 

good info, mine only works on the two highest settings.
the to do list grows.

 

If the fan switch on the dash doesn't have "physical" feedback, like a noticable click when it goes to the next switch setting, the switch itself is probably bad.

 

well when i move the switch i feel it hit each setting so it dosnt feel dirty but i can try cleaning it with electronic cleaner

 

The connector in my dash to my switch was physically burnt/melted. I had to rewire everything.

Switch was fine and the typical low setting was fried on my resistor