W211 E320 A/C problems. Live data photos of working and non-working

[ROLLGUY]

I have two W211 E320's to compare- one with perfect working A/C, the other not so much. The one with the problem has had the heater valve replaced (factory part), but that did not fix the problem. With the A/C on the coldest setting, I get some "cool" air from the right dash vent, and warm air from the left. I scanned both cars with my Icarsoft MB II in live data, and got some comparisons. From the car that works I got -99 on both in-car temp sensors (N70b1 & B10/4). On the car that does not work, I got 38.50 for the N70b1, and 35.07 for B10/4. (See photos 1 & 2).
The other screen with the compressor torque and consumption differs as well. The car that works was 15 & 350, the non working 18 & 690 (see photos 3 & 4). The remaining screen shows the refrigerant temp and pressure. The working car: 36.80 & 11.50, the non: 31.80 & 7.10 (see photo 5), photo 6 on the next post.


From looking at the data, I can assume there is something wrong with one or both of the in-car temp sensors? Admittedly, I don't know much about these systems. I do know that the refrigerant has a good charge, and I assume the compressor is working.

[ROLLGUY]

Only 5 photos per post, so here is #6 for the non-working system.

[resto108]

Swap overhead control panels so you have one good temp sensor in each car? I had a bad lower temp sensor B10/4 and the AC still worked, I just found the code one day looking for something else. I want to say it was reading -99 also. You can still feel the compressor lines to tell if the compressor is working.

[Zulfiqar]

Originally Posted by ROLLGUY

I have two W211 E320's to compare- one with perfect working A/C, the other not so much. The one with the problem has had the heater valve replaced (factory part), but that did not fix the problem. With the A/C on the coldest setting, I get some "cool" air from the right dash vent, and warm air from the left. I scanned both cars with my Icarsoft MB II in live data, and got some comparisons. From the car that works I got -99 on both in-car temp sensors (N70b1 & B10/4). On the car that does not work, I got 38.50 for the N70b1, and 35.07 for B10/4. (See photos 1 & 2).
The other screen with the compressor torque and consumption differs as well. The car that works was 15 & 350, the non working 18 & 690 (see photos 3 & 4). The remaining screen shows the refrigerant temp and pressure. The working car: 36.80 & 11.50, the non: 31.80 & 7.10 (see photo 5), photo 6 on the next post.


From looking at the data, I can assume there is something wrong with one or both of the in-car temp sensors? Admittedly, I don't know much about these systems. I do know that the refrigerant has a good charge, and I assume the compressor is working.

These systems are variable displacement and hence can severely screw up the mechanic in false diagnosis - best way forward in these cars is to check the system charge if you can, I can bet the one with bad cooldown is low on charge.

I have chased my tail off on these, first thing I check if the compressor is going to full 1amp consumption - if it is and I see the liquid side pumping high with the low side coming low - It confirms the solenoid is okay, next stop is to check the system charge load.