Hi folks - my 82 300sd has no air coming from the front vents on any setting. The AC was out of service when I purchased this car in January, but am now realizing that while air does come out of the defroster vents and out of the rear console vent, next to nothing comes out of the front vents (a slight amount of air comes out of the far left and far right upper vents).

If anyone has suggestions, I'd love the help.

Dave

No air out of the vents is usually caused by a number of different things. One thing that comes to mind is the vacuum elements behind the dash that control the airflow. If they are defective or not getting vacuum they will cause all sorts of problems with the airflow. I assume your fan is running and your getting the classic air out of the windshield vents.

There are five vacuum pods that regulate all the air doors in the system. The controls for those pods are a set of six vacuum relays that are sitting in a row right next to and slightly above the radio. You can access these relays by removing the carpeted panel on the right side of the transmission tunnel. The passenger kick panel must be removed first.

When the relays are exposed, get a Mityvac and apply vacuum to the output line from each relay. The output from the relays is the horizontal nipple from the relay. Each must hold vacuum. The one's that won't pump up require a repair or replacement of the vacuum pod.

Any pod in the system that leaks causes the entire system to fail. None of the doors will operate.

While you are there, you can connect full vacuum to the output that controls the center vents. You will then have air from the center vents, all the time. Then, you can control it via the three sliders on the panel. Otherwise, the system won't give you center vent air when in heating mode.

It's a bit of a project to undertake, but, start it one step at a time and ask questions.......on this thread........along the way.

Thanks very much for the detailed response Brian!

I need to pickup a mityvac (or maybe a coworker has one) and get working on this on a day off.

I'll definitely have more questions, and may try to post pictures with them to make it easier for everyone.