Cold Center Vents, Hot side 93 190E - PeachParts Mercedes-Benz Forum

meltedpanda · #1 04-25-2006, 10:47 AM

Trying once agin to help out a friend.
AC works but only cold at center vents and hot blows at the same time out of the side (far righ/left) vents

Place to start to look? ACC unit?
Tried search but really did not know what to search for?

softconsult · #2 04-25-2006, 12:39 PM

Sounds like vacuum pod failure. The pods control the various air flow flaps. On 300E you can check for vacuum leak with a MityVac at the connection junction box behind the glove box. No idea on the 190.

Steve

meltedpanda · #3 04-25-2006, 02:16 PM

I suspect that also but it does not make sense to have hot air, I could see no air or uncooled air but hot air

mctwin2kman · #4 04-25-2006, 03:27 PM

Vacuum leak on the W201 will result in full heat out the defroster vents. Pod failure and you could lose enough vacuum when that pod is selected to go to full heat as well. The W201 no heat comes out the center vents, only outside air and AC air. So you would not get heat out the center vents anyhow to match the heat of the outer. But you will get cold since the air never flows over the heater core to get to the center vents. But the AC will still come out them vents. So start looking for a vacuum leak. Since by design when the temp wheel is in the cold position and the AC selected the Aux pump will turn off and the heater valve will close. Maybe your heater valve is where the Vacuum leak is or maybe the vacuum leak is at the vent pod. When you select other vent controls on the CC unit do you get proper air flow at the correct places, in other words are the right flaps opened and closed to match your selection?

meltedpanda · #5 04-25-2006, 03:35 PM

I will check other positions and let you know, this is not my car so I am not sure. On my 126 I can get at most of the pods, what about this baby, are there places I can check without removing the dash?

mctwin2kman · #6 04-25-2006, 04:54 PM

Quote:

Originally Posted by meltedpanda

I will check other positions and let you know, this is not my car so I am not sure. On my 126 I can get at most of the pods, what about this baby, are there places I can check without removing the dash?

If you remove the glove box you can see the one for the blend/air doors. With the Gauge cluster removed you can see the one for the defrost and I believe one more. With the radio removed and the panel or cassete holder removed you get the legs one, vents one and the recirc door one. The vacuum distribution unit is under the passenger side vent and can be seen with the vent removed but better with the glove box removed. Check the vacuum check valve near the fuse box under the hood. should be one line coming from the engine through the firewall then to a Y splitter, one for the economy gauge that goes straight into the car, and one for the CC system that goes to a two way check valve and one line into the car and one line over to the passenger side and to the resevoir in the fender. There is also one more pod in the system, it is under the debri screen under the wiper on the passenger side of the wiper. That is for the Heater Valve, it closes to stop flow into the heater core.