My AC hasn't been working for 2 years, time to figure it out. I also noticed that my heat does not work very well in the winter, once I drive for 30 min it gets warmer.

When I first got the car, AC would work sporadically.

I did notice that when I turn on the AC, both AC lines in the engine bay are hot. Shouldn't one be cool and one hot?

Thanks to W220 Wiki, I managed to pull up the following errors on the control unit. However I'm not exactly sure how to go about troubleshooting these codes/sensors etc.
B1267 Communication Fault of A/C Bus - does anyone know where A/C bus is?
B1268 Communication fault of A/C Bus with Centre Vent Control Module (N18/4) - not sure what to do here.
B1269 Communication fault of A/C Bus with Multi-function Sensor (B31/1) - I found where Multi functional sensor B31/1 is. Should I test the voltage at this sensor?

I'm slowly leaning towards the compressor as it was quite loud when I first got the car (bearing). But before I take on such large job I want to make sure I'm heading in the right direction.

Should I also try troubleshooting duovalve?

TIA

 

When you allow the AC to blow, does the red "EC" light display? Or in your case (for the facelifted W220) I believe the button is "A/C Off".

 

Do you have access to DAS/Xentry?

I would read the error codes first and check if the refrigerant level is low.
Also, you should run your AC on the lowest setting for 4 or 5 minutes in the middle of the winter to keep the compressor lubricated.

 

On the W220 (and some other Mercedes models) there is no clutch on the AC compressor, so it always turns with the engine.

 

Really? I thought the clutch was controlled electrically by using an magnetic field

 

That was the standard method for many years, and still is for some vehicles - not for most late Mercedes vehicles.

 

Thanks for your replies guys!

I find the AC light/button confusing, but I have tried it with both on/off and it never gets cool.

I do not have access or know what those are, but I'm trying to get in contact with one of the experts at FCP Euro (they are literally 2 blocks away from me). So far, no luck. I know they have the STAR tool....is that what DAS/Xentry is (or is that an equivalent)?

Refrigerant level is the first thing I checked and filled. It's currently full.

I did notice that the compressor bearing was making loud noises initially when we first acquired the car (back then AC would work, but on and off.....sporadically).

That noise is now gone, however before I get the new compressor I want to make sure that's actually the issue. I know that's not an easy or cheap job (even if I do it myself, which I would).

The coolant lines are both hot (my son, who works in HVAC, said one of them should be cold and one hot when AC is running)....but again, I would like to confirm this before investing into compressor.

It seems like these errors don't really pin point to anything?

Would it be helpful to get all of the Temps/#s NR readings of the unit?

 

Have you checked/changed the fuses and relays?

 

Just checked the following one:

f33 40A Automatic temperature control;
Blower motor AC

I did notice a new code 1270 and 1271 -I think I'm going to unplug my sunsensor and see what happens....

I also took down the following NR#s of my climate control unit (car started)
NR
0 33.2
1 38.2
2 28.5
3 40
4 40
5 27
6 76
7 7 Bar
8 29
9 +1,3k
10 6.0V
11 8%
12 80%
13 98%
14 18%
15 51%

Few things jump out at me when I look at the reference file https://www.benzworld.org/threads/w2...menus.1632652/

NR07 - my refrigerant pressure is only 7 bar at idle, document says 14,3
NR08 - its only 1,3k vs 14,3k
NR10 0- blower control voltage is VERY high (6.0V) vs 1.8V on the document

Also sun sensor % numbers (NR11-NR14) are way off as well at idle.

 

1 more thing I forgot about, which is a bit troubling. I have a iCarSoft unit (OBD2 scanner), and upon selecting my cars parameters > manual > ACC mode > read codes, I get the following error

"Fault in communication with vehicle ECU
Please confirm:
1. this vehicle is armed with the system
2. This system is an electrical control system"

However, I can go into other options and it shows me all the parameters similar to NR readings. Also, on the climate control unit it does show DIAG icon when I have the reader plugged in

 

I assume that you've got the ignition turned on?

Try resetting the AC, there is an hidden menu and keycombo to do so.

Yes it is!

 

That's correct

I've done that # of times

Thanks, didn't know that. Is there a a way to test with these units to see if the AC compressor is bad? My iCarSoft doesn't seem to have that function

 

So I noticed that my 2006 does not have a clutch on it? Maybe it fell off? Or maybe my model didn't have it?

I'm thinking about taking the 300 gamble on the compressor....

 

See posts #4 & #6.

When the engine is running, does the center of the compressor pulley turn? If the outer pulley turns, but the center of the pulley doesn't, the compressor is locked up and the rubber cushions have sheared. If the center turns, it is not too likely to be a failed compressor, so that would be a bad gamble.

"I find the AC light/button confusing, but I have tried it with both on/off and it never gets cool."

The red light in the AC button ON indicates that the system (and thus the compressor) is OFF.


"The coolant lines are both hot (my son, who works in HVAC, said one of them should be cold and one hot when AC is running)....but again, I would like to confirm this before investing into compressor."

If the system is operating, the high-pressure line should be hot, the low pressure line should be cold.

The compressor is a swash-plate design. It turns anytime that the engine is running, and pumps refrigerant as demanded by the system controller by tilting the swash-plate as needed.

Go to https://w220.wiki/#WIS_83_Climate_Control

 

Thanks for replying Wallyp

Center compressor pulley turns as well as outer pulley (both rotate) with AC on or off.

Thats what makes me think its a compressor. But based on your previous sentence, maybe not.

I went thru it but I'm not sure how to troubleshoot the 3 codes

B1267 Communication Fault of A/C Bus - does anyone know where A/C bus is?
B1268 Communication fault of A/C Bus with Centre Vent Control Module (N18/4) - not sure what to do here.
B1269 Communication fault of A/C Bus with Multi-function Sensor (B31/1) - I found where Multi functional sensor B31/1 is. Should I test the voltage at this sensor?

I also got the following 2
1270 and 1271

I also looked up the service history of the car and managed to find the following:
48k - Heating/Air Cond
74k - AC Blows hot air/Evaporator (not sure if it was sensor or actual evaporator)