I can't remember where I saw someone say this, but I didn't see a write up for it anywhere so I thought I'd make one.
When you turn your vent selector to defrost, the A/C compressor kicks on to de-humidify the air. Maybe there's no sense to it, but in my mind, it seems dumb to heat the air enough to where it won't freeze up the system, then cool it off with the compressor and de-humidify it, heat it back up again (if the temp control is on "red"), then blow it at your windshield. Kinda seems like wasted energy, and there's not much of that to spare (especially on my 4-banger )
So this mod allows warm or cold air to be blown at your windshield without the A/C running (basically just shoots it through the same vents but without de-humidifying it first) Keep in mind that it won't be as effective as with dry air, but it will still work. Also, you can easily still turn on the regular defrost setting if you want more effective defrosting.
It's super easy and takes maybe 10 minutes.
First, remove your fan selector knob from the climate control panel. It just pulls straight off if you give it a tug. Be somewhat careful, as there is a metal sleeve that fits inside the knob that holds it snug on the little metal post that controls the selector. It should stay in the knob, mine came out and was difficult to get back on in the right shape to fit.
Next, use a dremel or something similar (if nothing else, a file will work, but be very slow) grind off this little bump on the knob
It should be slightly recessed into the knob when you're done. you may need to remove it and take more off later if it doesn't work.
Next, pop the knob back into place. If it worked, you should be able to turn the knob past the defrost setting 1 "notch"
It may take a little extra effort if you didn't take quite enough off. If it won't go, grind more of the bump off.
That's it! Your truck will now blow air through the defrost vents without running the A/C. If you want to defrost with the A/C, just turn the knob back to defrost. Easy! I know... you were expecting something difficult with all that buildup... sorry?
I suppose this was maybe a little too detailed, but I know I sure appreciate it when write ups are painfully thorough... enough for me to even follow
Anyway, enjoy your increased MPG, power, and clear windshield