Many times when I switch the AC on (or when I have the AC on), warmer air will come out of the side vents opposed to the center vents. It's sometimes the same temp, but sometimes noticably warmer, sometimes for only a short time, sometimes for quite a few minutes. I have known other Mercedes to do this, so I don't think it's a problem, but there has to be a reason?
Just curious because a friend told me my car was a POS because warmer air was coming out of the side vents. (He drives a 1999 Jeep Grand Cherokee (LMFAO!!) that doesn't do that)!!

__________________
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!)

This will happen when there is a vacuum leak. The doors inside of the heater/AC box are actuated with vacuum servos. If one fails, the blend is not right on the air.

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

ON many C-class cars the problem is the heater valve itself. Even though the valve gets an electrical signal to shut-off there is a physical water bleed problem. TRY clamping the coolant line at the valve with heater hose pliers. Normally if the car has a vacuum problem the center vent will open & close durning acceleration.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

David,

My '91 190E 2.6 did the same thing, exactly. Cold air from the center vent(s) and warm or hot air from the side vents during a long hill climb.

Going on level ground was no problem but making a protracted hill climb, the side vents would kick out hot air. Sounds like your car does the same thing.

I was told it's a vacuum leak and/or bad element (switch) in the center control console.

Never did fix it, just sold it so don't know what it took to fix it.

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

Our 97 C280 (wife's ride mainly) seems to have just developed this problem of side vent sending out warm air recently and I was wondering what may be the reason. Another thing I hope could delay on as funds is limited for now.

On the side, thanks for you folks advice on the knee panel removal and I was able to find wire to tap into later for hooking up radar detector. May be I could get some picture up when done hopefully this month.

Also, is it easy to drain and replace the coolant on the C280? Could someone point me to the location of the drain plugs and correct procedure? I am contemplating doing it myself if it is not too involving.Ont the other hand, I think I shall leave the fuel filter to the shop as the location seems a beast to get to with only jack stand.

Whoop, hit my return key inadvertedly.

Would like to say thanks again to David and MBenz before I logged off.

Have a good and productive week folks.

C.F.

I have the same problem..warm air on the side vent,How do start finding the vacuum leak? Where do you start?

Ron
93 190e 2.6

I know this is an old thread, but I now have the problem and there really wasn't an eventual answer.

Any ideas for me to check? I'll check out the vacuum connections if someone can give me detailed instructions on where to look/what to check.

Thanks,

__________________
1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
105k miles

1989 Mustang GT Cobra Convertible
43k miles

Can someone tell me how to check these servos, vacuum lines, and / or heater valves? I don't know where these things are.

These are my exact symptoms, though.

I have a 94 C280.

Thanks,

__________________
1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
105k miles

1989 Mustang GT Cobra Convertible
43k miles