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500Eboard Management
No heat from center vents
- Thread starter MK500
- Start date
OWNER - smoker (1995 E420) | Owners and Their Cars
All 1995 USA models of the 124 had the machine-finished wheels with clearcoat (aka 'High Sheen'), but only in 15". A good wheel shop can machine the face and replicate the look on a set of painted wheels, but it ain't cheap if you have to ship the wheels both ways. :spend:
You need to diagnose the functions of all six of your vacuum pods, to see if they are holding vacuum, or if any of the diaphragms inside have failed. You can do this at the vacuum tree next to the airbag - you will have to remove the airbag to access the tree. There's plenty of info here on the forum about how to dothat.
You should never get hot air from the center vents of the dash. Read the owner's manual, or the climate control service manual, for a description of how the system works.
EDIT: This is for models with automatic climate control (ACC), which was the only climate control offered in North America. Cars elsewhere with manual climate control may be slightly different. USA-spec cars will never deliver hot air from the center vents except briefly when transitioning between modes. See the owner's manual and climate control service manual for details.
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This is acturly not always the case. heres is Why.You should never get hot air from the center vents of the dash. Read the owner's manual, or the climate control service manual, for a description of how the system works.
All models no exeptions up to 1992 have only fresh outside or AC cold air blowing from the midel vents.
In 1992 there came an update (not related to facelift or model year) that had an ekstra flap opening in the vent case for the hot case to blow out there.
This is the case with Dual Zone Semi automatic Climate systems like most cars in europe has.
And the setting has to be none of the midel bottons pressed/activated meaning no red diodes must be lit up.
That will make the AC in automatic on/off mode as its needed.
And no recirculation on and no defroster on.
Then the midle flaps opens and blow out the same temperature of air as the side vents. hot when hot.
So if this feature should work on the Fully automatic 1 zone climate control system, you would need to try the same settings trasnfered for this.
It might not be the same funktion or working at all on these systems that most US cars came with standart. but at least some models acturaly are able to blow out hot air from the middle vents. if you want a combo with fresh outside air in the middle vents you just push the EC botton. then hot air can be chosen and will only get to the side vents. nad not the middle vents that will then act like the older systems.
Ive seen this HVAC casing out of a car and there is an added flap on there, so im not talking guesses or thoughts but facts.
Again im not 100% sure it works for the single zone fully automatic climate control system.
With Dual zone simi automatic Climate control system from 1992 and forth.
3 bottons in the midle of the 2 temperature setting wheels..
the 3 bottons has a red diode each that will lit up if the botton is activated/in function.
All of these has to be off. meaning no reciculation and No EC (AC off) or Defrost function activated.
Then you will get hot air out the middle vents.
Again if you chose the same function on the single temp wheel fully automatic climate control system, im not sure it would have that same features or they just made it an the dual zone climate.
With Dual zone simi automatic Climate control system from 1992 and forth.
3 bottons in the midle of the 2 temperature setting wheels..
the 3 bottons has a red diode each that will lit up if the botton is activated/in function.
All of these has to be off. meaning no reciculation and No EC (AC off) or Defrost function activated.
Then you will get hot air out the middle vents.
Again if you chose the same function on the single temp wheel fully automatic climate control system, im not sure it would have that same features or they just made it an the dual zone climate.
See the edited information in post #5 above.
If you get cold air from the center vents, but zero hot air, everything is normal for a USA-spec car.
The button referred to by @BRABUS124 as the “defrost” button in the middle row on the two zone klima is not a defrost button. That button activates the drying function of the ac system, and is supposed to remove moist on the inside of the windows. The drying function will start under certain circumstances by itself, but is possible to activate manually if needed. It’s all in the owners manual, albeit poorly translated and a bit confusing, the German original is way better:
On the topic on how the middle vents operate, on my 420 they were the same temperature as all other vents when using the ac (not pressed in EC button). On the 500 I have to check. On older 124’s I had, with or without ac, they are outside temp so needs to be closed otherwise it will be a bit chilly inside. I do now also own a 300E after my dads passing, and that car has the full fat klima, I’ll test on that car too, once I get it assembled again, but that’s another story!
On the topic on how the middle vents operate, on my 420 they were the same temperature as all other vents when using the ac (not pressed in EC button). On the 500 I have to check. On older 124’s I had, with or without ac, they are outside temp so needs to be closed otherwise it will be a bit chilly inside. I do now also own a 300E after my dads passing, and that car has the full fat klima, I’ll test on that car too, once I get it assembled again, but that’s another story!
Yes defog the name must be ofcause
Today, I notice I get no air from center vents from any setting. What do I check first before opening up the dash?
Assuming this is a 124 chassis... pull the glovebox (or passenger airbag) and test all 7 vacuum lines at the manifold. All should hold vacuum. Any that do not, need the pod replaced or repaired.
We have a HOW-TO here on the forum for replacing W124 ACC pods. Sadly, only some of the pods can be replaced without removing the dash.
Another benefit of the W126 over the W124 ... all six pods can be replaced without removing the dashboard
If you find a pod's diaphragm has failed, you can get replacements from Klima Design Works here in Maryland. More information is here:
Matthew James is a great guy. Call him if you need diaphragms.
Another benefit of the W126 over the W124 ... all six pods can be replaced without removing the dashboard
If you find a pod's diaphragm has failed, you can get replacements from Klima Design Works here in Maryland. More information is here:
Matthew James is a great guy. Call him if you need diaphragms.
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