Red powdery stuff on ac compressor? (Pictures)

While optimized idle was kicking in, this popped. I was able to catch it before it went away:

SPN 876 FMI 1--inactive HVAC front control unit, A/C clutch data valid but below normal operating range.

Sounds about right.

This was a day or two ago. That was was probably the event that spewed forth that mysterious red powdery substance.

 

Yeah, you're right. And maybe the dripping coolant was messing up the AC clutch temporarily and throwing that SPN...

This is complicated. Some Sherlock Holmes ####

 

So, the plot thickens...



First of all, I did find the coolant leak, little drips from the metal pipe near a mounting. I wouldn't even worry about it, except it's messing up my belts with it's red residue. So that mystery solved.

But... Secondly... the round part in front of the AC compressor pulley (the clutch, I presume), keeps stopping and starting every like 30 seconds. See the first two pics. Meanwhile AC keeps running normally. I am outside the truck and not turning AC on and off. Is it supposed to do that? I honestly have never really paid attention to that thing before.

In short, do I have both a bad AC and a coolant leak?

 

I indeed didn't know how the AC clutch worked. But I asked you, and now I do, kinda. Admitting ignorance and asking questions is part of the whole analytical mind thing

And thanks for the advice. It's not really a hose, more like a metal pipe with integral mounting. I'm sure Freightliner will charge me a slightly overpriced $250 or something for it, and then i will replace it and no more red gunk. Thank you and everyone else for your help. I learned things.