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Discussion Starter #1
So I just got 2004 s600 and have a climate control problem. I am decent with tools and I have done a good handful of hours reading and researching through the forums. So here is my dilemma:

1.- ACoff button on

2.-Only really hot air blows from the heater unless on "LO" then its ambient more or less.

I did the diagnostic which I found here on te forums with turning the temps to 72 degrees...

NR1: 0C
NR7or8 (cant remember) 3.4 bars

so it is my understanding that the inside temp sensor is not working and my r134 needs to be recharged. Neither seem like they will be too hard to fix. I found the thread on how to recharge (seems like most other cars) and I found out where the sensors are. I however do not know if I should replace both sensors or how to do it. I figure the dealer will have part numbers but I would like to get the sensors somewhere cheaper. I am goin to spray some dust cleaner in the vents to make sure they arent just dirty but any help would be greatly appreciated! The thread below pretty much shows how to get to the sensor on the dash it seems.

I am a new benz owner and also new to the forum so if I have overlooked the answers, my apologies.

thanks
 

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Discussion Starter #2
Does anyone have experience with this problem? Called dealer today to order the inside temp sensor on the climate control unit and the said I had to get a whole new unit.... Any info would be awesome.

Thanks
 

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2005 Mercedes-Benz S500, 1982 300SD, and about 4 other parts cars in rubbermaid bins in the garage
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306 Posts
Oooo sucks its the one integrated into the climate head unit.

Yeah can't think of any other way except forpulling unit and sending to:

 

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2004 Mercedes-Benz S55 ///AMG, 2006 Mercedes-Benz E350
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I may be missing something from your original post but if you turn off AC(light on) you say hot air blows in, what temp setting do you have when this happens?

In other words, if it 30 degrees outside and your inside temp setting is 70 degrees, even with AC off, the system will heat up the air to match your setting of 70 degrees without the AC running. In this example AC will reduce humidity levels if it was on but you will still get warm air in.

Sorry if I have misunderstood your point.
 

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Discussion Starter #5
the two outer vents will always blow hot air and never cool down because the sensor is telling them its 0 degrees (i checked by holding down the rest buttin and its NR1=0'C). the only way to get them to blow cold are is by putting it on "LO". The middle vents above the center console (which also have their own auto mode when you push the dial until the little auto light comes on) will stop blowing and/or blow cold air because the sensor for those is working fine. I believe they run on the sensor that comes up NR0 which is registering pretty accurate. My outside temp sensor is working correctly also.

So if anyone can give me any advice on testing the sensor or an easy way to replace it that would be awesome. My ac seems to work fine now with a recharge but it would be nice to just put everything on auto for less than a grand. haha

thanks
 

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04 S600, 99 BMW 750iL, 97 BMW 750iL and many others.
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I have the same year and model 04 S600.
I guess my charge is ok, but NR1: 0c. did you ever get this fixed somehow?
My A/C blows a little colder air, but never blows real cold air.
 

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Discussion Starter #7
no i didnt but my a/c works reat and blows cold air. my problem is with my heater and only blowing really hot air out of the dash because my temp sensor that is located in the overhead light console seams to be out. I bought the sensor from a scrap yard but never fixed it. just realized I have to turn down the fan when the heater is blowing cause it thinks its cold in there. I would pull the info from your ac and make sure your system has the right amount of "bars". you can also reset those fault codes through the ac code menu. look in the encyclopedia to figure out what im talking about if your confused.
good luck
 

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1982 240D, 1986 560SL, 1987 560SEC, 1990 300SE, 2002 E320, 2002 SA 500SL, 2005 S500, and others
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I posted the repair to the overhead console, and I am sure that is your issue. Unfortunately my repair only lasted 6 months or so and then the leads broke again. This time they broke so close to the sensor I can't solder them again.

I pulled the consol out pending the replacement of the sensor (not available separately from MB) and have not put it back in yet. The good news is with the overhead sensor gone, the system looks to the remaining sensor and the climate control goes back to working fine.

You do loose:

Sunroof control
Auto wipers, auto lights
Some interior lights

So if anyone sources the sensor, let us all know.

John
 

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'02' S500 (W220)
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586 Posts
I posted the repair to the overhead console, and I am sure that is your issue. Unfortunately my repair only lasted 6 months or so and then the leads broke again. This time they broke so close to the sensor I can't solder them again.

I pulled the consol out pending the replacement of the sensor (not available separately from MB) and have not put it back in yet. The good news is with the overhead sensor gone, the system looks to the remaining sensor and the climate control goes back to working fine.

You do loose:

Sunroof control
Auto wipers, auto lights
Some interior lights

So if anyone sources the sensor, let us all know.

John

Did you check this Site out for a replacement? http://www.meas-spec.com/downloads/ESCC_Epoxy_Coated_1K3A351.pdf
 

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I posted the repair to the overhead console, and I am sure that is your issue. Unfortunately my repair only lasted 6 months or so and then the leads broke again. This time they broke so close to the sensor I can't solder them again.

I pulled the consol out pending the replacement of the sensor (not available separately from MB) and have not put it back in yet. The good news is with the overhead sensor gone, the system looks to the remaining sensor and the climate control goes back to working fine.

You do loose:

Sunroof control
Auto wipers, auto lights
Some interior light
So if anyone sources the sensor, let us all know.

John
Hi john that was a great post and seems to have solved many people problem, but I think it is not the sole problem or solution.
My left right vents were giving different temperature, nr01 (overhead cabin sensor) was broken and nr 3 nr 4 were 10-15 degree c apart.
nr01 was broken, I repaired but no difference in vent or cabin temperature.
So I undid the repair and had a gas refill. The ac guy said the sensor will not Affect ac performance and that low gas can cause different vent temperatures.
After gas refill, ac worked superb, both/all vents and nr 3 and nr 4 were only 1/2 degrees apart and showed temperatures as low as 4 (outside temp 40+).
Next day I again repaired the sensor as well and accessories performance is as good as without sensor.
 

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W124 E420 : W220 S500 : W222 S550
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Interior sensor repair

After experiencing inconsistent cooling but then freezing the car when the AC is placed on max setting, I checked the interior sensor using the service menu. It read 0.00 C. When it was actually about 32C (90F) in the car. Knowing that the only replacement involved the entire overhead console at a high price, I decided to repair the sensor. It should be noted that the sensor is a standard thermistor. A temperature sensitive resistor giving a known resistance at a known temperature. These resistors (thermistors) are quite robust and typically the fault is a broken/shorted wire. This was the case , a hair thin solid wire was broken on the sensor. The wires are fragile so the first thing I did was snipped the sensor along with 1/2 " of its wire. I put a piece of electrical tape about an eight inch wide around the two wires on the sensor to help physically stabilize them. Both wires in one wrap of the tape with the tape touching in the middle for electrical isolation. Next, It is easy to see the two solder points for the sensor wires on the board. I had two stubs of wire left on the board after snipping my thermistor away ( one snipped one broken). I used two pieces of 26-28 gauge wire about 3 inches long and soldered them between my sensor and the wire stubs on the board. I suggest using stranded wire to add flexibility to the sensor wiring. I then routed my sensor wire OUTSIDE of the fan housing to avoid the reason it failed in the first place, the sensor fan blade was hitting the wire for 10 years eventually breaking the wire. I ran it outside and then tucked the sensor to its original location . I bent the wire over the lip of the housing (were it passed from inside to outside of the housing) and duct taped it to the housing. I did a dry fit to check the wires and eliminated a pinch point for my wire routing, and this should be done before reassembly. It has worked flawlessly since ( about 4 months). And I no longer have the subtle ticking that was my fan hitting the sensor wire for the last few years.

One thing of note, although I did not check the thermistor resistance, I have found that no OEM uses a custom thermistor, it is an off the shelf item and can be checked to verify temp/resistance characteristics and then replaced with a similar resistance thermistor for about $5 . If my wire had been too short to solder I would have gone that route. also there are two really good solder points on the bottom of the board that I verified to work if the solder points in the original location (on the sensor fan assembly) are unusable. their location on the board is close to the normal solder location (on the fan assembly) with no other solder points nearby.
 

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2006 c230
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i have that fan implausible that the thermisteris connected to.I opened up checked it and wire was broke .i fixed it with new resistor .the fan still is implausible any idea on what to do to make it stop it runs without the key in ignition as well nonstop 24/7
 

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Hi,

Hi, I'm no HVAC expert, I don't get a lot of problems with them in NW Scotland, probably because it's not working flat out all the time in our mild climate :wink

Unusual that the Fan runs without Ignition on :confused:

SDS Codes, Testing and Actuations will get you to it a lot quicker than "it might be this, it might be that". Get some Codes and post them up, and someone more experienced may be able to help. :wink

If you look at our Encyclopaedia there is a way to get it to give you Codes by pressing buttons in a sequence, if you don't have access to SDS.

HTH,

Cheers Dave
 

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98 ML320, 01 S500, 15 GL350
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587 Posts
I have the fault symptom, center vent cannot blow hot air. However, the NR.0, NR1 and NR2 readings are correct. Should still open the overhead bin to take a look at the sensor? Thanks in advance!
 
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