I have an '09 kw w 900. Recently the a/c in the cab has began going out. The blower stops blowing but the air is still cold in the vents. When this happens the sleeper air continues to work normally. Mhc has said they can't find the problem. Anyone had this problem before? It always seems to start working again before I can get it to a shop. But its quit for as little as a couple hours and as long as a week.

Sounds like a fan motor to me, I have put several in my W9 over the years

They would slow down, stop, start squeal or quit altogether

That or a bad connection on the motor or switch, many mechanics are nothing more than parts changers and have little to no diagnostic skills and don't really care if the do or not.

repete, that's not nice, speaking the truth there like that! ;-)

Find the blower motor for the cab and check the wiring for it IF you can check it and its not wrapped up in a wire cover. Try to check the entire length of the wire for a break. Pull the plug if you have to, make sure its not dirty then plug it back in good and tight and see how it goes. If it continues, its definitely the motor then. I've seen automatic windows work intermittently, it was 1 wire in the door/cab crevice, in the rubber boot where it broke. Every now and then the 2 ends would touch just enough for it to work. Drove us nuts trying to find it because it was in the rubber part where it shouldn't have broke and was wrapped with some 35 other wires.

Oh well I worked in a body shop for 20 years and watched the 'old' guys slowly retire off and be replaced by the next generation, many who had no idea how to heat shrink metal or what caster/camber or toe was (I'm not talking camel toe Roadie!). And the mechanical side has more or less gone the route.

"Every now and then the 2 ends would touch just enough for it to work."
I just had a similar problem with my 12v cooler. It worked ok for a couple years but never really seemed to be 100%, it quit the other day and I thought about just replacing it but I'm cheap.
I brought it home and took the plug apart first, turns out the ground wire was never soldered completely and over the years the resistance would build up heat and melt one small wire strand at a time. As each strand broke it would increase the resistance on the remaining strands and started a cascade type failure, Two minutes with a solder gun and better than new! Saved me about $80.

#cameltoelivesmatter

I was wondering if you'd catch that.

Exactly, I'm a younger guy myself and yet I complain how the old ways don't work anymore. We got a truck fixed by an older guy who refused to listen to the computer and what it was telling him was wrong. The computer kept telling him it was something other than the computer on the truck. Nowadays though, its all about what the computer says even if that is wrong. My wifes car had a problem with cutting off, yep a Chevy Cobalt. Tried to tell me it was the O2 sensor.............told them to take their $100 scanner and shove it, an $8k machine I had access to said it was the computer, now fix the computer only. Next time I went there for the same stalling, again tried to tell me it was the O2, told them it was replaced 6 months ago so F off!