Climate control (AC) was working fine during my drive... later I turned it off. A short while later (minutes or whatever), I turned it back on... the unit lit up and worked properly, but there was NO airflow... no nothing. I checked the voltage to the blower via the N-22 read out (hold REST), [menu # 8], and it flashed 8 and then would flash NOTHING (s/b voltage). Hmm, so I was a little confused. I then turned the Temp to HI, and heat came out; heat worked as normal.
Later on, I had the car off and tested the diagnostic codes via the PBU also (Rest + (front) Defrost), and I got the same 4 diagnostic fault codes (28, 60, 80, & 82, all "intermittent") that are always in the system (rendering it irrelevant, partially?). Well a short while later, while driving, I turned the A/C on, and it started working. The Climate Control has been working (AC) ever since... so I must be in the clear regarding that...!

Well when, and after, this problem occurred, I noticed the dash (no center, only side) vents would open on the freeway when driving at a high speed... but they would close moments later! This is still happenning... from time to time the driver side & pass. side dash vents open for a few moments and then close when driving fast.
And to add to that, whenever the Climate Control Unit is switched off, there is a random annoying high-pitched squeak that comes intermittently and lasts for a few seconds... if I hear the sound, and quickly turn the CC on, the noise ceases.
ONE last little thing... this "problem" has come to my attention in the past 10k miles or so: After turning off the car (thus CC turns off), the vacuum flaps close as designed... but about 5 or 6 seconds later, I will hear another vacuum flap close (sounds like passenger foot well (feet heat or recirc?)...

I'm assuming I have a vacuum leak in the system somewhere...
Any pointers?
Thanks a bunch everyone!

(((I swear, the moment my A/C started acting up, my stereo stopped acting up! Atleast I got some good with the bad... )

I truly appreciate everyone's help... and a special special Gilly! You're great. :p

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

1. I’m not sure if I can help you much on this one, but sounds like some connection(s) are loose or has hairline cracks and changes with movement and/or temperature (metal expanding and contracting). I had this problem in my 190 when I was checking the values on all the 5 sensor that feeds info to the push button controls. I didn’t have a tester like you but the “intermittent” that you mentioned was exactly every 20 seconds in my case. This pointed me to the outside temperature sensor. Sure enough when I hook up the DMM to it the readings would fluctuate when I wiggle the cord around. I didn’t see any cracked cord so I try resoldering the connections. Hook up the DMM again got study reading, I test for correct resistance at different temperature by first putting it in the freezer then heat it up with my wife’s hair dryer (not to long or to hot!). Hope this helps some.

2. Some people in this forum suggest the push button control unit itself. What you do here is open the unit up and resolder everything, from age the solder becomes loose and/or has hairline cracks from vibrations. This should be your last resort.

3. The other reason I’m here is to ask you if you ever got your Flashers fixed. I got the same problem in my 260E, the high-beam works but flashers don’t. See and answer back at this post: Flashers


Thai GI sends...

__________________
GI but not GI Joe
They call me "The Thai GI"
Thai in the US Arsenal

I ASSume that this problem is on the C-class. The fresh air vent vacuum diaphram is a common failure on this car. TRY using the "ec" button when this happens. IF the problem goes away then you need to have that vacuum element checked!

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I have come to the conclusion that the RECIRC vacuum line has a leak in it. Based upon my observations, the "default" position is RECIRCULATE mode... IE the flaps close when the climate control is switched off. THey open on the freeway.... when I have the CC on economy and fresh air, air BLOWS (very fast) through the vents... and when I push RECIRCULATE, the airflow slows down to normal.

Air is forced in through ducts (below windshield, forcing open flaps....? Must be a leak I suppose... seems like a pretty sure thing...
Would a fault code appear if so? (I have 28, 60, 80, 82... all "intermittent" vs "continuous" codes.)

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)