Are there foot heating vents in my 83 300D? - PeachParts Mercedes-Benz Forum

MonsieurBon · #1 11-18-2004, 10:43 PM

Are there foot heating vents in my 83 300D? And if so, why don't mine EVER turn on?

It's cold here. I'd like my feet to be warm, not my dried-out eyeballs!

What do I have to do, route some dryer hose from the dashboard vents down to my feet?

kerry · #2 11-18-2004, 11:29 PM

Yes there are footwell vents. You have either a bad vacuum pod at the vent actuator, a bad switchover valve or a defective heater control. Most likely a bad vacuum pod. It's to the right of the accelerator. It is visible once the under dash panel is removed. It can be replaced by working on it from both footwells. It has a bayonet type fitting. A plastic latch must be pushed in and the pod turned to remove it. If you do a search on my posts, I posted instructions how to replace it about a year ago.
Test the pod by putting a Mity Vac on it and see if it actuates with vacuum. There are rebuild kits and new pods available from George ?????.

rg2098 · #3 11-18-2004, 11:30 PM

There are foot vents, I have found mine not to put out quite as much heat as I would like. Both driver and passanger side flaps are controled with one actuator, I would recemend you check it. Its on the driver side behind the center councel, easy to access with the under dash cover off (easy to do). Theoretically they should always be on when the climate control is in use.

kerry · #4 11-18-2004, 11:39 PM

It is my understanding that the foot well vents are not actuated when the heater is on defrost. (far left button). They should be actuated in all the other positions except 'off'.

rg2098 · #5 11-18-2004, 11:43 PM

grr you clicked the button before I did and beat me to it, yes your right, every mode except defrost and off.

MonsieurBon · #6 11-18-2004, 11:55 PM

Ouch.. Those actuators are about $50. Any chance of rebuilding one, or just leaving it stuck open?

300DandTD · #7 11-19-2004, 07:57 AM

RG2098 I have eye balling your avatar. Is that your car purchased from E Bay in the last year ? It had 211K on it and was from Texas. Same car ? I came very close to bidding on that car my 85TD is the same color. It looked very good from the pictures.

rg2098 · #8 11-19-2004, 03:52 PM

Yupm thats the one, the car is very very nice, but the pictures made the paint look a tad better then it is. Paint is excellent for being origonal in a southern climate, no dash cracks either. Even though the paint looked nicer, he did not mention that the A/C compressor was replaced and the old stuff put back it, nor that the cruise works. Overall i'm extrodonarly happy with it. If your ever up this way drop me a PM and maybe we can get together.

Eskimo · #9 11-19-2004, 06:50 PM

Quote:

Originally Posted by MonsieurBon

Ouch.. Those actuators are about $50. Any chance of rebuilding one, or just leaving it stuck open?

If you really want to do it on the cheap, you can simply remove the vacuum actuator entirely, and then connect something to the mechanism so that you can manually open and close the vents. I've seen it done by attaching a plastic cable tie to the lever where the actuator would connect, and then allowing the "tail" of the cable tie to extend into the passenger footwell area a little bit. It needs to be stiff enough to be able to push and pull on the mechanism, but a fairly modest cable tie is enough to do this.

I can take no credit for invention of the above trick; it's just the way my 300D was when I bought it. I've since replaced the actuator.

By the way (and someone please correct me if I'm wrong here), I don't think the footwell vents are always open when the automatic climate control is on. I think they're open when the ACC is trying to blow warm, and closed when it's trying to blow cold. I think the center vents are just the opposite.

mplafleur · #10 11-19-2004, 06:59 PM

I have also noticed that when I put my knee bolsters back in that my feet aren't warm anymore. They used to work, so I will check my pods again. I kept all the vacuum relay accessible.

I bought replacement diaphrams for $5 each. (I think) I will look for the link...

boxscar · #11 11-19-2004, 07:49 PM

i have that problem with my 300d. i found the only way to get heat down below was to make sure the climate control was off when the engine started and warmed up. then turn it on after the engine is running. when you stop for a taco and shut the engine off, turn the climate control off. then when you want heat on the feet again, turn it on. otherwise it will put all the air out the dash vents.

MonsieurBon · #12 11-21-2004, 02:54 AM

Quote:

Originally Posted by eskimo

By the way (and someone please correct me if I'm wrong here), I don't think the footwell vents are always open when the automatic climate control is on. I think they're open when the ACC is trying to blow warm, and closed when it's trying to blow cold. I think the center vents are just the opposite.

I took out the underdash panel and looked at the vacuum pod. It's fairly accessible. Problem is, I tried actuating the lever it attaches to and it didn't blow any air out of that hole.

So given what you're saying, I should get the car warmed up before I try that. I was trying it with the car cold in the garage and turning the heat control to max and the blower at max.

So it sounds like it's intelligent enough to not blo cold air on your feet, eh?

#13 11-21-2004, 10:18 AM

Quote:

Originally Posted by MonsieurBon

Ouch.. Those actuators are about $50. Any chance of rebuilding one, or just leaving it stuck open?

Try this:

http://www.autoluxmbz.com/

Louis.

Eskimo · #14 11-21-2004, 10:55 AM

Quote:

Originally Posted by MonsieurBon

I took out the underdash panel and looked at the vacuum pod. It's fairly accessible. Problem is, I tried actuating the lever it attaches to and it didn't blow any air out of that hole.

So given what you're saying, I should get the car warmed up before I try that. I was trying it with the car cold in the garage and turning the heat control to max and the blower at max.

So it sounds like it's intelligent enough to not blo cold air on your feet, eh?

OK, just to be clear, we are talking about a vacuum actuator that's oriented horizontally, and is located directly behind the ductwork leading to the foot vents, yes? I'm thinking about the vents down low on the left and right side of the center column of the dash, with one vacuum actuator that uses a linkage to operate the flaps together (one on each side). If I'm using the wrong nomenclature here, then please, someone correct me.

I think the "smarts" of the ACC system decide when it should "try" to open those flaps, but if you're mechanically reaching in and moving things, I don't think it can matter what the ACC "thinks" about the temperature of the car. If you're physically moving the mechanism to open those flaps, then I think air should come out of them. You should be able to directly see if they're open or shut - the flaps are right there where the air comes out.

As an aside, I'll repeat that I think that the ACC is also supposed to close off the center dashboard vents when delivering heat (deliver more to your feet, and help give your eyeballs a break).

rg2098 · #15 11-21-2004, 11:50 AM

Quote:

Originally Posted by mplafleur
I have also noticed that when I put my knee bolsters back in that my feet aren't warm anymore. They used to work, so I will check my pods again. I kept all the vacuum relay accessible.

I bought replacement diaphrams for $5 each. (I think) I will look for the link...

I had the same problem, turned out the bolsters were not installed correctly by the PO and I installed them the same way. I steped back and thought about it and discovered that there are black guides for the air that attach to the bolster that covers and block the vents unless properly installed.