P38 weak blower motors
 

So it's been a while since I've posted anything regarding my trusty (haha) P38... I was ALMOST missing having something to work on!

When I turn on the fans to high, a lot of noise happens, I can definitely hear the blower motors working, but a very weak stream of air comes from the vents. All of the settings work well, meaning that it switches from blowing towards the feet, middle, and top, but just not very much air comes out. Heat works, AC works, but just not a big volume of air coming out.
I did notice that the yellow relays were burned/discolored pretty bad - they looked original, so I replaced them and they promptly melted, so I looked at the fuse block and it was cracked and melted too, so I replaced it with a brand new one from bputah at the cost of like 300.00 USD
That did fix the melting relay problem, but unfortunately it still produces a very weak stream of air, even on high.
I took out the pollen filters and ran it without them to test, but they weren't terribly dirty in the first place, and no debris in the vents behind them. It seemed like it blew out a touch more air when I ran it without the filters at all, but definitely still weak.
Any suggestions would
Be GREATLY appreciated, as this is starting to drive me mad!
Thanks to all in advance!
-Murph

Measure volts at motor? Check ground that motor eventually goes to? Check vent dampers for operation, the heater ECU has to open them in the right sequence.

do you have a little testbook emblem lit up on your hvac control panel?

Thanks for the suggestions, Savannah... Ill look into them one by one....
Drossap - no lights whatsoever.
-M

it not a light per say just a picture of a book

Drowssap - is the picture on the actual heater controls as opposed to the dash? My LCD display on the heater controls isn't working :( i can see a backlight but the numbers are all scrambled like someone pushed on it really hard or something. I've seen a fix on here for that, and have been meaning to do it. (Would be nice to be able to see the external temp and stuff anyway... maybe I should do that first ? Anyone ever done it? Kind of figured it was a pain in the ass, so it got pushed down the priority list pretty far.
I wish I had more time to get every single thing in tip top shape, as I really love the truck, but I just have had to spend most of my time getting it road-worthy and keeping it running well.
As always, thanks in advance for the advice!