Alrighty pelican parts gods, y'all have gotten me this far, hopefully someone can give me some advice here. I've been lurking this forum for the past 3 weeks (I've owned my mercedes 190e for all of 3 weeks) and y'all have helped me greatly. I've learned a ton about the car and I hope to offer some advice of my own in exchange at some point. Here's what's going on in my engineering masterpiece that I just can't get my head around:

-There is no heat or AC regardless of where the dial is turned to.
-The AC button does not cause the clutch to engage (could be linked to low refrigerant but I haven't plugged a gauge to it) but that doesn't explain not having heat either
-My mode selectors don't change where the air comes from (I think that means I have to pull the dash to get to my vacuum blend door solenoids
-The CCU is in good condition, we pulled the board and redid a few questionable solder joints
-The relays and fuses are fine, we checked them with a multimeter and that all checked out nicely (around 64 ohms of resistance across the relays I believe is what the meter said)

So where else should I look before ripping the dash apart? I haven't checked the mono valve yet, gonna do that after my test tomorrow and I'm probably going to give it a charge as well. not having heat makes me think I have a mono valve issue but I'm not properly versed in the Mercedes ac system or any ac system to be honest (even though I learned a good bit about them in my thermodynamics and applied thermodynamics classes, That doesn't help me with the mechanical systems, just how much heat and cooling I should be getting). This car is way too nice to not have ac and heat, also, winter is coming and I don't like being cold. Thanks in advance!