floor vents not functioning/opening, HVAC 86' 300E W124

[JFAZ]

Hello everybody!

I have an 86' 300E that I purchased nearly six months ago from the original owner. The floor vents fail to open when the correct button is pressed (confirmed by owners manual). I assume they are operated by a vacuum, however I have no idea where to begin my troubleshooting.

Any suggestions or advice would be greatly appreciated.

All other functions of HVAC work great.

Thanks,
Jerry

[Cap'n Carageous]

I had to replace that white box with the red tube in the center of the photo. It's a vaccum element that opens the footwell airbox doors. It's a bad job.

[JFAZ]

Thanks for the pic Cap'n!

I have now completed my floor vent quest! Everything operational!

I discovered that the 86' is unique to other w124 models because it has two vaccum servos that operate the floor vents. When one has a leak, it stops the functioning of the other because lack of vaccum suction. After the one unit was replaced problem solved. It was only necessary to remove the center climate control unit, and front side floor carpets for this job.

Jerry

[Cap'n Carageous]

You lucky rascal, you. Be on the lookout for the rest to fail though. The one that controls outside air coming in to the cabin can make you think the air conditioner compressor ain't working. It won't shut off that 100 degree outside air and the system can't overcome it. Good luck!!

[mbtjc]

I don't think my floor vents are opening either on my W126. Is it worth fixing this? I can live with it if it is going to entail ripping the entire dash and console apart just for a little box! That or it is going to cost me out the..well you get it. So what's the story on my car?

[Cap'n Carageous]

Judgement call on your part. Any car used as daily transportation should be kept up. If you're not gonna keep it up it will deteriorate quickly.

[mbtjc]

Ok, well will it require just pulling the wood around the switches or pulling the entire dashboard?

[Cap'n Carageous]

Sorry, can't help you with with the 126. My experience is limited to the 124. O. K. you 126 guys, help the man out!

[BigRichard72]

I have this exact problem on a 1987 300e, how bad a job is it to replace the outside/fresh air accuator, and where is it?

Originally posted by Cap'n Carageous
You lucky rascal, you. Be on the lookout for the rest to fail though. The one that controls outside air coming in to the cabin can make you think the air conditioner compressor ain't working. It won't shut off that 100 degree outside air and the system can't overcome it. Good luck!!

[JFAZ]

I have a follow-up problem that has occured after repairing my problem w/ the vaccum servos. It involves a short circuit somewhere that kills my interior panel illumination. If you think you could provide any insight please click below.

Thanks,
Jerry Faszer

http://www.peachparts.com/shopforum/showthread.php?threadid=34091&highlight=300E+fuse+interior

[Cap'n Carageous]

Big Richard; It is at the top of the air box, the big black box in the middle, and behind it between then the box and the dash. It's really a ***** to get to, but it makes all the difference in the world as far as the performance of the climate control. Here's how I figured out mine was bad. A/C compressor died and was replaced. Charged new system with R134. It cooled but not well. It would never cool enough to come off High. I could look under the car and water is pouring out of the evaporator box drain. That says the system is working. So, it had to be an airflow problem. Quick trip to the expert and I knew what I had to do. Ordered an MB Body and chassis manual from 1-800- ForMercedes and jumped in. Took me a 10 hours but I saved $600 in labor. Would I do it again? Yeah, I bet I could do the next one in 9 hours!:p