I have heard there is a few relay mods to do on my 91 W250, what are they and what are their functions? My heater fan dosnt seem to blow very fast, just wondering what to do about it.

Kasey

 

cut a hole in the heater box and vacuum out all the junk that got in there over the years... your fan will be able to blow air through the truck now. There is also a set of resistors behind the heater controls(i think you can access them through the glove box if you don't have A/C) I just ran a jumper from the power circuit to the 3 positions on the switch as i either have the heat on full blast or off. and it still blows some with the blower off.

 

https://www.dieseltruckresource.com/...t-t102027.html