My W212

Have some ac problem for few weeks. Blowing very very just weak cool air. Now, have a health check with icarsoft for any codes. No fault code. But i got that N70b1 temperature sensor shows -50°C, which is faulty, right? So, please advise me where this sensor is? Million thanks

DFWdude

There is a temp sensor with fan in the overhead console. It runs all the time (24/7). Don't know if this is specifically related to your code, as there may be other sensors with fans..

Here is a related thread... https://mbworld.org/forums/e-class-w...nsor-code.html

jvakos

I’m glad you posted this! I have the same iCarsoft scanner and on my 2015 e63 it shows same -50 degree value on that “interior temperature sensor with integrated fan”

did you figure out what it was? I’m trying to figure out what sensor to replace.

The scanner doesn’t show that there’s a code on that or a fault, which is weird?

My W212

No worries. That reading is always -50C in my icarsoft mb3. I don't know why but I have wasted some time to replace that sensor. Finally, I found that my ac only ran out of refrigerant. So, you may first check refrigerant if you don't have a cool ac. Good luck !

My W212

The n70b1 is in the overhead control panel.
Some pictures of tearing down for your reference.






Replaced with a new one which has the same resistance.

jvakos

@My W212 thank you so much for the photos and location info for that sensor. I'll open up the OHC and see if perhaps it needs to be cleaned (assume no, it just broken). My AC shows fully charged but I'll double check that. Mine is a 2015 E63 and strange coincidence is when i installed an aftermarket intake system from BlackBoost the issue (seemed) to start happening. The intakes are open filter boxes and I assumed somehow that all the heat from the engine bay since the boxes were open were making it more challening for the AC to cool the outside air, but the issue all happens if I use the recirculate/cabin air option....

super appreciate all your findings here that you shared. !!

kajtek1

If the scanner reads -50C on good sensor, that means the scanner is not supporting the reading.
I always advise to start AC troubleshooting with temp sensor calibration test, as this is the easiest way to start and often can find the culprit without getting your fingers dirty.
Checking refrigerant pressure on variable output compressor is tricky.
I usually leave the car in hot spot for the test and when I start AC with interior temp about 40C, that will give me couple of minutes at max output to measure the pressure.
Fully charged system on hot day should exceed 30 bars, when 25 seems to be acceptable.

CaliBenzDriver

Thank you Kris for pointing that out - I think you right about 3rd party handheld scanners have limited support for each and every chassis.

My updated Autel Maxidiag has been showing me partial faults with :

1. OCP TempSensor bogus Temp
2. TPMS tire pressure data memory
3. RFK Rear camera calibration

Where using a Xentry confirms no problem present.
So that's an additional grain of salt to keep in mind with 3rd party "compatible" scanners.


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MBDarryl

Hello, ive discovered this is the issue I have and have managed to get the OCP board out - can you steer me on how to test, replace and/or repair? Id be mega grateful

CaliBenzDriver

What is going on with your OCP module ??
Show us picture of the circuit board as you see fit.

Use your cReader Elite scanner to help read values and test procedures.

Note that not all "MB compatible" scanners support all functions of all modules... ie. "mileage may vary!" Autel Maxidiag scanner showing wrong data.

MBDarryl

My N70b1 sensor was returning an error on my Carly diagnostics so after taking the OCP apart I wasn't sure how to test it directly, and I can see 'Mt W212' had managed to replace the resistor. It was very dusty so I've cleaned it and put it back in the car. Will be testing it later today - fingers crossed!!

CaliBenzDriver

What sort of value was your Carly scanner showing:
a crazy -50F temp (bad scanner)
or
a little bit lazy 63°F due to dust collection?

How about your HVAC Controller live data...
🤞

MBDarryl

Hi CBD, massive thanks for msg!!

All sensors were reporting a realistic temp value, but the OCP sensor was -50! On inspection, it was very dirty so I thought id try a deep clean and see what impact it has, ive yet to test it up to temperature yet, nad have reset all error codes ready for a check in the coming days.

Im not sure what the HVAC control live data is? I was going to leave it a few days and try it on Carly again to see what it discovers...

MBDarryl

I have now tested [after a thorough sensor clean] and can see that the cabin temp appears to be adjusting, although I think it's not calibrated: eg.
- on 17/16 degrees its cool, but not 16/17 cold *feels more like 20/21
- but on 'LOW' it goes to full chill
Feels like the temp settings could be adjusted as the AC is obvs working fine, as is the heat...

Question: is there a calibration exercise I need to do so the 'head unit?' knows the correct temperatures? Or should I consider replacing the temp probe in the OCP? Which looks like it's above my soldering skill level

Massive thanks in advance 👍

CaliBenzDriver

Hi MBD, CBD here...
I think you've gone as far as simplicity goes. There are multiple issues involved with the true cabin temperature.

One is the hot coolant is always circulated through the dash as there's no shut off valve. Its nice in winter, not so much in summer heat. The whole idea behing that is to dry the misty evaporator and prevent windshield foging.

There are experimental ways to reduce the engine heat by enabling the piston oiling near 1K.RPM.

Also you can bump the AC efficiency by insulating 200F engine heat out of the high pressure line.

HVAC actual live temperature data are found using a suitable scanner on the AAC Module. Some handheld scanners are more limited than others.
The pet scanner around here is the "cReader elite MB by Launch" priced around $150 AMZ.

Clean/replace cabin filter for good flow.

Lube the squeaky cabin blower fan helps push air through the system.

Enjoy regulated temperatures.

jvakos

@MBDarryl let me know what you find as my OCP sensor also reads -50F on my iCarsoft MB2 scanner and my AC seems to only blow cold when I set it to LO setting. I did a recharge of my AC and that has helped but you cant seem to get cold air blowing if you set it at 60, 62, 64 etc it only comes on when LO is set....

I have yet to attempt to open up the OCP and inspect/clean that as I'm fearful I'll break some of the plastic tabs while trying to remove it and never get it back on... maybe i just need to do that.

CaliBenzDriver

This drove me nuts for years.... -50F is associated with bad scanner, not with a bad sensor unless scanner is recognized to support for N70b1.

In other words your issues are not caused by this good sensor.

Read the HVAC module for active issues.

DeanMassy

It runs all the time (24/7). Don't know if this is specifically related to your code, as there may be other sensors with fans..

CaliBenzDriver

yes, we have a similar sensor on the dash near the RPM tach.

It's strange your sensor runs all the time ...

these sensors are dust sensitive to get all plugged up.

MBDarryl

Hey,

OK, so cleaning this OCP sensor didnt work And like me you are now looking at options to replace this sensor!
My current logic is: the HVAC will only blow cold on 'LO' as this setting doesn't need to know cabin temperature! But with all other settings, HVAC will be out of wack - as the OCP sensor is telling it it's -50. So it will continue to deliver heat...

BTW: I also worried about breaking a plastic tab when taking OCP apart, but it came apart ok with some logical effort - remember there are screws under the center object and the sticker
Once unscrewed, you don't have to separate both sections to get the PCBoard out.

Good luck bud

MBDarryl

Carly does read all other sensor values so I'm thinking this OCPsensr is faulty?? All other ACC areas are being read, and returning realistic values - but im happy to be proven wrong, if its not this sensor - what else would it be I wonder....

CaliBenzDriver

ACC reads its sensors well besides OCP Temp shown as -50.

This LIN sensor works well regardless of limited support compatibility by some scanners.

MBDarryl

So do you think I DON'T have a sensor problem, and that I should try something else?

Im not very car-technical so don't know how best to diagnose where else the problem might be

CaliBenzDriver

I used to ask myself the same question until I used a Launch scanner that showed that sensor was 100% FINE.

What are you trying to diagnose?