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So, I still have a problem with my outside temp sensor. When I pull the grill, there is nothing connected to the sensor, and I can't find the the wires that connect. Now, I have a problem with the climate control. I set it at 68 degrees, but it is too warm. After reading many old threads, it seems that there are about 6 or 7 inside temp sensors. However, I also notice that the outside temp sensor can affect the inside temp. Do I likely have a problem with one or more of the inside sensors, or can my outside sensor be causing my problems?
 

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The outside sensor for the climate control is mounted in the air intake area at the base of the hood by the wipers. It measures the temperature of the air coming into the system.

The sensor you're describing, if I get your drift, is down in front of the car. That's the sensor for the outside temperature gauge, which shows up in the instrument cluster.

The two sensors are not related.
 

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The outside sensor for the climate control is mounted in the air intake area at the base of the hood by the wipers. It measures the temperature of the air coming into the system.

The sensor you're describing, if I get your drift, is down in front of the car. That's the sensor for the outside temperature gauge, which shows up in the instrument cluster.

The two sensors are not related.
Yes, I was talking about the the outside sensor that feeds the instrument cluster. A few years ago, a MB mechanic told me (referring to my SL500) that the outside sensor feeding the gauge also had an effect on the climate controls inside the car. However, that didn't make much sense to me. Maybe it tells the car whether to send air conditioning or heat when set at 70 degrees. In any case, does anyone know an easy way to trouble shoot which sensor is causing the car to get uncomfortably warm?
 

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Yes, I was talking about the the outside sensor that feeds the instrument cluster. A few years ago, a MB mechanic told me (referring to my SL500) that the outside sensor feeding the gauge also had an effect on the climate controls inside the car. However, that didn't make much sense to me. Maybe it tells the car whether to send air conditioning or heat when set at 70 degrees. In any case, does anyone know an easy way to trouble shoot which sensor is causing the car to get uncomfortably warm?
The climate systems on the R129 and W220 are completely different, so what a mechanic may have told you about one has little to do with the other.

It may be your warm temperatures are unrelated to the sensors, and you have another problem like low freon charge or the pneumatics on the dampers not working properly. I'd check the simple things, like freon charge first, and tear into the electronics of the system as a last resort.

Good luck.
 

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Is the Outside Temp Sensor (OTS) used to calculate how much to cool the cabin? For example, when I set my cabin temp to 65 degrees, I would imagine that the OTS reads that its 80 degrees outside and determines how much to cool the cabin? Btw, I just found out that I have the same problem. I just want to make sure I understand the problem before I take it to the shop.
 

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Is the Outside Temp Sensor (OTS) used to calculate how much to cool the cabin? For example, when I set my cabin temp to 65 degrees, I would imagine that the OTS reads that its 80 degrees outside and determines how much to cool the cabin? Btw, I just found out that I have the same problem. I just want to make sure I understand the problem before I take it to the shop.
Why would the OS temp sensor have anything to do with the inside cabin temp? Think about the thermostat in your house. You set it for 75, it reads how much different from 75 the temp in the house is and heats or cools until the house is the temp you set. It could be 125 degrees outside or 10 degrees outside--all the thermostat controlling the HVAC system cares about is how hot or cool it is inside. The AC in the car runs at higher speeds if it needs to change the temp a lot, then settles into slow speed to maintain it--without the need to query the OS temp.

Good luck on your repair.
 

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Back to the original question from "louisbr", if you have located the sensor and there is nothing attached to it, then wires are cut or missing. The sensor itself looks kind of like a probe, metal piece in the front, round plastic seal around it (where is attaches and holds into the front left grille), it is about the length of your average pen.

I agree with the people above, the outside temp sensor has nothing to do with inside temps. If you set it to 68 and still feel warm, then lower it some more to find your comfort spot. I keep mine at 70, but depending on the day or night, I need to change it by 2-3 degrees to make it more comfortable.
 

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The outside temperature sensor is located in the left front bumper. It records the temperature and sends the information to the left front SAM control unit. It operates between -40' and +85' Celsius. The SAM control unit sends the information to the Automatic A/C Push Button Control Module which then changes the air temperature lightly.

The Sun Sensor is located in the middle of the air inlet in the engine hood. It tracks the sun in four quadrants and transfers the measured values to the air conditioning bus. Based on this information the Automatic A/C Push Button Control Module adapts the outlet temperature and blower speed.

Hope this clears it up for everyone.
 

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There are two temperature sensors in the interior, one in the roof control module and the other in the AAC push control module. Both are have aspirator blowers to give a high degree of temperature measurement. The one in the roof control module is used at outside temperatures less than 10' Celcius and both are used at outside temperatures greater than 10' Celcius.

Seems like the entire system is quite sophisticated and not like our thermostats at home!!
 

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I need to locate the exterior temp sensor that displays channel NR.02 on the diagnostic menu in the climate control display. I'm seeing the temperature value fluctuate between -2c and +25c with an actual outside temperature of 22f. Is this part of the sun sensor or in a completely different location?
 

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NR.02: is the Outside/Ambient Temperature Sensor (B14). It is located in the small left front air scoop below the front bumper. See here:
https://w220.ee/Outside_Temperature_Sensor_(B14)

Contrary to what several posters have said above its operation is crucial to the performance of the W220 Automatic Climate Control.
Quoting WIS,
Accurate temperature control is achieved by monitoring the various temperature sensors such as:
  • Left Heat Exchanger Temperature Sensor (B10/2)
  • Right Heat Exchanger Temperature Sensor (B10/3)
  • Evaporator Temperature Sensor (B10/6)
  • Outside Temperature Sensor (B14)
  • Sun Sensor (B32/2)
  • Interior Temperature Sensor in ACC Pushbutton Control Module (N22) (N22/b1)
  • Interior Temperature Sensor in Overhead Control Panel (OCP) (N70) (N70/b1)
  • Temperature Sensor in Rear A/C Evaporator outlet for vehicles fitted with Code 582.
As I understand it the Outside Temperature Sensor (B14) affects the volume of the variable displacement compressor. We don't want our S- Class passengers to get too cold do we? By that I mean if the ACC is set to 22C then that is what the internal temperature will be within a degree or two. The actual controlled temperature inside the cabin varies as the sun intensity changes and as the sun angle changes. The more intense the sun and the warmer it is outside (as sensed by NR.02: ) then the greater the displacement of the compressor and the greater the cooling effect produced by the ACC. Also if the sun is full on one side of the car then that side controlled temperature will be a bit lower than 22C to compensate for the extra solar load. Brilliant isn't it?
 

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Ricebubbles thank you for that thorough explanation. What I don't understand is why the NR.02 temperature fluctuates while the outside temperature displayed in the instrument cluster stays consistent. Are you sure there isn't another exterior sensor that is dedicated to the HVAC system? If I monitor the NR.02 temperature I notice when it drops to correct outside temperature the interior of the car gets warmer but then it rises the interior cools off again. While all of this is going on the outside temp in the cluster stays steady and does not fluctuate.
 

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Can't explain that.
When I reversed engineered the W220 ACC (car air conditioning is a passion of mine) I used a hair drier to apply heat to the various sensors and watched the value change as per the data base here http://www.benzworld.org/forums/w220-s-class/1632652-w220-s-class-automatic-climate-control.html

What you could easily do is get an On Board Diagnostic (OBD) Wireless Adapter and read out the values via the OBDII port onto an iPhone or Smart Phone.
See here: http://w220.ee/Code_Readers

I may be that there is a wire loose some where or even a software glitch. Have you tried removing the battery thus resetting everything?
 

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Can't explain that.
When I reversed engineered the W220 ACC (car air conditioning is a passion of mine) I used a hair drier to apply heat to the various sensors and watched the value change as per the data base here http://www.benzworld.org/forums/w220-s-class/1632652-w220-s-class-automatic-climate-control.html

What you could easily do is get an On Board Diagnostic (OBD) Wireless Adapter and read out the values via the OBDII port onto an iPhone or Smart Phone.
See here: http://w220.ee/Code_Readers

I may be that there is a wire loose some where or even a software glitch. Have you tried removing the battery thus resetting everything?
Ricebubbles ,

When I look at my Nr.11, Nr.12, Nr.13, and Nr.14 they all read 0. The problem I am having is when my ac blow warmer as it gets hotter inside and blows cold when it gets cold inside. Any suggestions?
 

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See here for what those numbers mean.
http://www.benzworld.org/forums/w220-s-class/1632652-w220-s-class-automatic-climate-control.html
They show the data coming from the 4 Quadrant Sun Sensor (B32/2) which obviously has a problem. (Wires, sensor etc).
Fix this before worrying about anything else.
It will have an impact on how well the ACC works.
http://w220.ee/Four_Quadrant_Sun_Sensor_(B32/2)
Ricebubbles. Thanks for the reply. I found that my 4 Quadrant Sensor is working. The problem I face now is even more baffling. When my ac is on, as the number on the NR.01 increases, so does the warmer air coming out of my vents. As it decreases the air gets cooler.

I am of the understanding that temperature that is showing on NR.01 is the temperature from the overhead cabin sensor. I would assume as that number went up that cooler air would be sent out of the vents.

Is my assumption incorrect?
 

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....I would assume as that number went up that cooler air would be sent out of the vents.

Is my assumption incorrect?
Yes and No!
Parameter NR.01: In Car Temperature Sensor in the Overhead Control Panel (OCP) will show the actual temperature near the OCP.
NR.00: In Car Temperature Sensor in the ACC Pushbutton Control Module Front Compartment will show the actual temperature lower down the cabin.

Assuming it is winter [summer] and you have just switched on the car the ACC will push out warm [cool] air and you should see both NR.00: and NR.01: increasing [decreasing] as the cabin warms up [cools down]. When the cabin has reached the set temperature they will obviously stabilise at the required temperature. They will most likely differ by a degree or two as they are physically separated by about a half a metre.

From then on they should stay at or near the required temperature.

Once stabilised if the OCP temperature sensor senses and shows a lower [higher] value than the set temperature, then the ACC should push out warmer [cooler] air in order to bring the cabin back to the set temperature.

A good way to test both sensors is to gently blow some warm air from a hair drier into the sensing ports once the cabin temperature has stabilised and note the temperature of the air coming out of the vents. It should get colder.

I can make my car do this just by warming my finger tips by rubbing them together or on something and then placing them in front of either of the two sensors grills. I can watch both NR.00: and NR.01: change slightly and feel the change in the outlet vent temperature when I do this.
 
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