Hot air from the sides only

[benzguy300]

In my 91 190E I get hot air coming from the sides and cold from the center vents I did a search but I didn’t get an answer. Maybe someone that had this problem can help me out

[Frank Reiner]

This information is from a W126 publication, but the Automatic Climate Control (ACC) is at least similar, if not exactly the same for the W201.
In the three button positions that have double arrows, and when in Heating Mode, outside air will normally be emitted from the center vents, though occasionally warm air will come from those vents. The occasionally bit is a function of the cabin temperature, the programming of the ACC, and the condition of the vacuum actuators.
If the ACC is behaving correctly in all other respects, the vacuum actuators are the likely culprit, in that the blend door remains set to outside air and does not switch to heated air.

[benzguy300]

Thanks Frank I’m going to try a different AAC unit I think that’s the problem now That you mentioned how it works i already checked the vacuum actuator that goes in the engine bay

[Paulwho]

The center vent of the 190 does not have access to heated air, outside air or ac air only.

So in the winter or summer the center vent is the same as the outside air until the air conditioner is engaged.

[Mxfrank]

Originally Posted by Paulwho

The center vent of the 190 does not have access to heated air, outside air or ac air only.

So in the winter or summer the center vent is the same as the outside air until the air conditioner is engaged.

Yup! In the winter, just close the center vents. You'll only get cold air through them. If the sides are blistering hot, it means there's a vacuum leak...somewhere. The default is full heat whenever and wherever the vacuum system fails. Unfortunately, tracking it down isn't always easy. Begin with the vacuum connectors in the engine compartment, and go from there. Don't be too quick to replace the pushbutton unit, it's a lot of money and not usually the problem.

[optimusprime]

Idea is to keep driver awake,so the center vents push out cool air only ..

[gatorblue92]

Are you always getting hot air from the side vents regardless of the CCU temperature setting?