just one

 

Hi, could anyone sure that the interior temperature sensors are all bypassed when ac set as LO in both side?
The answer could surely enlighten how I can deal with my ac problem (compressor or sensors). Thanks.

 

There is no way around it you have one bad sensor, even if your compressor is bad you still have to replace the sensor. Use a hairdryer (not too close) to the sensors, and see how they change temperature readings.

 

But I don't understanding why the scanner still detected -50C from the OCP temp sensor when fuse 17 (for the entire OCP) is taken out. Really confusing me. Any idea?

 

Most likely -50C is default reading with open, or shorten circuit.
Since you pulled the fuse, it has to be open.
Don't read the notes who apply to 30 years old technology. You have way more advanced system.

 

Looking for a 10k ohm NTC thermistor for OCP n70b1 replacement. As to the B value of the thermistor, some has 3435, some 3694, and more..... I don't know what is this but just a try of 3435 one, given that I can not find any exact information about the specifications of OCP N70b1 sensor. Great appreciate if you could give me some idea.

 

Scanned again focusing on the changes of 3 readings when revving the engine to 4500rpm in p shift (ambient temp 28.5C)
A. Refrigerant pressure (hold revv at 4500 rpm)
B. Evaporator temperature (hold revv at 4500 rpm)
C. Power consumption of refrigerant compressor (1 hold revv at 4500 rpm, 2 step pedal for several quick revv from idle to 4500 rpm)

Results:
A, pressure going up from 12.8 to 13.5 bar gradually...

B, evaporator temp going down slowly from 30.9 to 30.1C.

C1 (hold revving at 4500 rpm), power consumption of compressor do not have too much change (stands around 0.74A)

C2 (strong revv 4 times from 700 to 4500 rpm in p shift), the power consumption plused from 0.74 to 0.87A (see 4 peaks in pic below)


Question below. Appreciate for any idea...

Could the above diagnosis confirm that the compressor works fine, but just the OCP n70b1 sensor give it a super low temperature signal (-50C) which stop it to work harder to cool down the refrigerant in the evaporator ?

 

You have scanner I am not familiar with, but I don't see you ever did sensor calibration test?
1 outside sensor shows.54C, the other 28C . What da hell?
Also giving us refrigerant pressure without what part of cooling cycle it is worthless.

 

How can I do this calibration test? I am using a icarsoft MB v3.

 

Based on this first post you did your compressor works fine. If it didn't you would not get cold air from any vent.

Lots of testing etc. suggested by another member but it really seems you have a mixing gate issue that has been brushed in earlier posts. Your scanner should show the mixing gate position values? Or does it not?

Also the -50C is an odd value. If that is true, how could you get cold air at all?

Also, your scanner shows evaporator temperature at above 30C. With that you would not get any cold air from any vent either. Was your temp setting at LO during all these scanner results and you got cold air on the right side? If yes I think you have a scanner that does not read data correctly. In my two MB cars the evaporator temperature is at around 4C pretty much all the time if the system can keep up with the cooling demand.

Refrigerant pressure fluctuates based on engine speed and how much cooling you get from air flow thru the condenser in front of the car. Your pressure seems to be in the right range.

 

See reply #17

 

Copy. Thanks

 

Sensor calibration test was done this morning. All temp readings are the same except N70b1.




N70b1 OCP temperature sensor replaced this afternoon with a 10k ohm NTC thermistor (tested ok with a meter) then put everything back to the car.

Sadly, the scanner still show -50C and ac could not blow out cold air.


Pics of n70b1 replacement shared below. Any more better ideas on my bad ac?

Before replacement


After replacement



Interesting.... the old senor was checked in order. It has around 9k ohm reading in about 29C. Reading owered when heating up (by hair dryer).


Seems that the n70b1 sensor itself is not faulty and not the root cause of my ac problem.

Appreciate for any ideas on my bad ac. Refrigerant charge? Or other test? Please help! Thanks.

 

Bottom line that sensor reading is not reaching a module. So the problem is electronic. Have you checked for continuity. S-Prihady has been looking at bad solder point on different boards lately, maybe he knows how that sensor travels to the SAM.

 

W212.
9 kilo ohms at 29C seems to be a healthy 10K ohms sensor.
Attached link is a typical 10K Ohms NTC thermistor
https://www.bapihvac.com/wp-content/...stor_10K-2.pdf

The OUTSIDE temperature of a W212 is always hotter than ambient by 10-15C, if the car is stationary for long.
This is because the OUTSIDE temp sensor is at the front bumper left side ( mine ) and it get blown hot air from engine bay and radiator fan
One need to do at least 60 KM/H for a few minutes to get proper outside air temp.

CaliBenz was the one doing the prevention/curing of bad solder joints and/or soldering the push type pin ....and up to the OCP.
I stopped at Rear SAM only .... , me dare not do my front SAM and according to CaliBenz, fron SAM is all proper soldering, not pushed type pin like rear SAM.

Let me see WIS wiring, for now I am in agreement with S.Madman that probably the -50C means open circuit to temp sensor/thermistor.

.

 

W212,

What is your actual W212.??? chassis code ? Mine is W212.065
E350 has quite many engines version... I am confused.

 

W212,

DISCUSSION 1 : Blending Air Flap
Find in your iCarsoft MB v3.0 the menu where you can see the air distribution/belnding flaps movement and position. I recall my v2.0 has it and yours should too and I think your V3.0 may be able to do
actuation, since it claimed to be bi-directional ...yes ?




I assumed your aircond is 580 code and not 581



================================================== =


DISCUSSION 2 : The N70b1 interior temperature thermistor.

Observe the description....WITHOUT CAN as in CAN-BUS. So it is using LIN. ( el-cheapo slower data communication type/method/protocol...whatever the proper term is )




I suspect, and PROBABLE ( but not guaranteed), that the hardwire for the temp sensor is below :



N70 means Overhead Control Panel. N70/3 is just the variation of the same thing.
DO note, 3rd party scanner can ID a module or sensor on that module by the wrong name/part-number. N70/b1 means module N70 and its b1 sensor, same as N70/3b1. If N70 is Jack, N70/3 is John, both are OCP.


Now, I gathered all I can on the airconditioner system. Convert it to PDF if you so wish.
I do not believe a sensor on the OCP can effect the HVAC to any greater extend than a mere correction value, it can't make your HVAC one side hotter.
Sensor at OCP gives sun radiation level I think.

Good luck.....
PS : Me will also try more reading on the HVAC and see what I can find out.

 

W212,
I am using iCarsoft MB v2.0

No need engine running, only need Ignition key in Position 2 ( ready to crank, all warning on dashboard lights up )
If you have a charger, use it because this will draw 16 amps.

In ur iCarsoft MB v3.0, to to AC - Air Conditioning N22/7 Menu
>>> View Data

>>> Set aicond blower fan to say 2 bar. Press AC compressor button so that aircond is running ( except its compressor )...........

>>> Choose Actuator motors M2/6 ( Left blend air flap actuator motor )



Use F1 to choose all 6 data fields






Read the data as is without touching temperature control of Left side and make sure temperature is set at say 19C, anything cooler than your ambient temperature.
You will get data line 1 and 3 and 4 at zero or zero%, see below...meaning your air flap is choosing COLD air.





Now, to activate the air flap to give HOT air, set the temperature to HIGH.



And then the data line 1 will be full travel value of 1968, 3 & 4 will be 100%





Now go to the healthy right side flap and do the same experiment to know how a good one would respond.

Even though the flap has to travel say 90 degrees or more, the % ( data line 3 and 4 ) will only be either 0% as CLOSED or 100% as OPEN or Zero for data line 1.
Any travel value numeric for data line 1 say higher than 1, that means the flap never made it to totally closed or zero.
The same for data line 3 and 4 percentage.

Is the % or 1968 data value is linear ? Probably.
Say a 90 degree is the TOTAL opening/closing of the flap, the percetange probably represents the angle accurately.
The value of 1968, can be roughy visualized as 1968/90 = 21.86 data points per 1 degree of flap movement.

Have fun............... troubleshooting

 

W212,

If your car has SLIDING ROOF option 414, your Overhead Control Panel uses CAN.

THEREFORE.......... my sketch below, does not apply to your car for the possiblility of hardwire for the N70/B1 temp sensor. It is probably processed by the processor to tag along information on the CAN-BUS higway.
Whatever type of your OCP is, CAN-BUS or not, you need to trace the PCB board copper traces , that maybe the problem since you can get 9 kilo ohm for the temp sensor at 29C while it is removed from the OCP assy.


Attached PDF, if your OCP uses CAN BUS

 

Thanks so much S-Prihadi for your wonderful advice and info.
Mine is 212.056 with the engine 272.
The AC code is 580. Sliding roof 414.

 

W212,

You are in luck, I think I can explain what N70 ( Overhead Control Panel ) is in good detail.
It so happened I was stripping down Front SAM N10/1 wiring diag for components/options which are not found in my car, as such I can spot what N70 ( N70, N70/2 , N70/3 same same ) is actually is.

01. N70 is NOT a module in some cars. I repeat, you can not scan for N70 in some cars, it does not exist for cars other than the one with option 414 SLIDING ROOF which uses CAN BUS to the OCP.
So one has to adjust his troubleshooting method.

02. For the N70 without CAN BUS, which my car is........ there is no dedicated fuse for N70 junction board. Let's call it junction board.
For its interior light, N70 get constant power (30) from Circuit 58d of Front SAM N10/1 at connector A pin 1 of N70. This also feeds Rain-Light sensor B38/2.
This constant power 30 is pumped out from N10/1 Front SAM from its connector 13D pin 9.
Circuit 58d is also known as Instrument Panel Connector Sleeve.

For a special +12Volt power feed, N70 at connector A pin 1 get power from N10/1 Front SAM connector 13D pin 3 which is actually from N22/7 HVAC control module. So N10/1 Front SAM is only a broker here.


03. So, which modules uses the physical service of thi Junction Board N70 OCP ?
For my car :
- Using LIN, it is the Rain/Light sensor B38/2
- Using LIN, it is the Dimming Inside rearview mirror A67
- Using hardwire for signals 1,2,3,4 of buttons of Control Module of Panoramic Sunroof A98 which is at OCP.
- Using hardwire for the N70/b1 interior temperature sensor actual installation location.


So, where does N70/b1 interior temperature sensor wire run from and to ? ( for a car with NON CAN-BUS N70 OCP )
From N70 connector A, pin 2 and 3 ( NCT- and NCT+ ) goes to Front SAM N10/1 connector 13D pin 7 and 5 and then out again to HVAC module N22/7 at N10/1 Front SAM connector 5C pin 13 and 14.
See cordinate 44 upwards





See attached WORD.docx of SAM10/1 Sheet 4 of 10, stripped down for my car and non stripped down version.
The only way to pass you guys a non compressed JPEG is to either zipped it or keep it in Word.docx and you guys can zoom all you like.


Oky doky...... enjoy the reading



ADD : Can your scanner see N70 OCP ? Now that you mentioned you have option 414 sliding roof and your OCP N70 is the CAN BUS type ?
I am very curious

 

Thanks once again S-Prihadi. Could you do me a favor to use your icarsoft to check the refrigerant pressure as well as the evaporator temperature when the engine is running at p shift?

In my icarsoft, the pressure is about 11 to 12 bar and the evaporator is always over 30C. Apart from the faulty n70b1 connection, I suspect my refrigerant is low, making unable to make any cold air.

 

How can I confirm whether my icarsoft scanner could see n70 OCP or not? Please help!
Yes, 414 sliding roof option is confirmed by the VIN check. But I don't know if my OCP N70 is a CAN BUS type or not. What should I do to check? Thanks

 

Looking back, I am now thinking of leaking refrigerant instead of faulty n70b1 because my ac problem is not an overnight issue. In fact, it started blowing "not so cold" air three weeks ago. Then, it blowed only "cool" air in both left and right sides. Two weeks ago, it started to blow "weak cool" air in right hand side (warm air in left). Finally, only warm air at both side.....
I suspect that my faulty n70b1 problem (-50C) existed long before and the system may ignore this stupid extreme temp reading....

 

Well, if your scanner can't see N70 even if your N70 is the CAN BUS type, there might be a chance that it does not yet qualify as a MODULE and it can not be seen by even MB Xentry.
A MODULE does more things. So perhaps it is only about CAN-BUS communication available for your car, where in mine is only LIN....and both of them are still junction board ... he he he