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I have a 2005 C230 sport and the AC is not working after replacing Front SAM. DTC B1046 is present (refrigerant pressure sensor B12/2). After perfroming several tests, recharging the refrigerant and hours of reserch I belive its the coding in the used SAM I installed. I used my Launch scanner to backup my origanle SAM and loaded it on the used SAM. But during my reseach Iv'e found that other peaple have had issues with the hw and sw transferring. I have two questions.
1. How would I check this?
2. And is it possible to correct it if I don't have the original SAM anymore?
I have not worked on your specific issue, but I have replaced my front SAM and found that some coding using the Mercedes STAR system may be needed.
Check post #21 on this thread. This shows the screens for the Front SAM "Control Unit Adaptations" in the Mercedes STAR system. My issue was with the Reverse Gear coding, but I see that there is an option for the Refrigerant Pressure Sensor. I don't know what the options are under that menu, but I think that you may need to make a change in that menu to fix the problem with your AC.
I suggest that you find a shop that specializes in Mercedes and ask whether they have the STAR system available. If you find a shop with the STAR system, they should be able to determine what is causing your problem and fix it. I'm not familiar with the Launch scanner you used, but it may not have all of the capabilities of the STAR system. As you can see in the thread I linked, my mechanic copied the coding from my original SAM and attempted to load it in my new SAM and that didn't work. This may be one area where only the Mercedes system will work.
I have not worked on your specific issue, but I have replaced my front SAM and found that some coding using the Mercedes STAR system may be needed.
Check post #21 on this thread. This shows the screens for the Front SAM "Control Unit Adaptations" in the Mercedes STAR system. My issue was with the Reverse Gear coding, but I see that there is an option for the Refrigerant Pressure Sensor. I don't know what the options are under that menu, but I think that you may need to make a change in that menu to fix the problem with your AC.
I suggest that you find a shop that specializes in Mercedes and ask whether they have the STAR system available. If you find a shop with the STAR system, they should be able to determine what is causing your problem and fix it. I'm not familiar with the Launch scanner you used, but it may not have all of the capabilities of the STAR system. As you can see in the thread I linked, my mechanic copied the coding from my original SAM and attempted to load it in my new SAM and that didn't work. This may be one area where only the Mercedes system will work.
Good luck.
I have the same options on my scanner and have tried them both. Also the sam and the AC module are showing different pressures.
Also the sam and the AC module are showing different pressures.
This is a guess, but do you think the differences in the pressures indicates that the SAM isn't communicating with the AC module? Is it possible that one of the connectors on the SAM isn't seated properly? Also, does the new SAM have all of the fuses and relays that the old SAM had?
I did some more testing and found that the ground for the refrigerant pressure sensor B12/2 at the Front SAM has 0.01 Volts when the key is on. I then disconnected all the wires from the Front SAM and check them all for continuity with ground and didn't find a short. This means that there is a short to positive inside the Front SAM right?
Last edited by outdoorjunke; Feb 10, 2025 at 12:22 PM.
I don't have enough expertise to answer your question.
The only information I can add is based on my limited experience. In this context, is the replacement SAM a new one or a used one? I'm asking this because the first time I replaced the SAM, I installed a used part. The used part failed in about a year.
If you installed a used part, you should consider installing a new one. If you installed a new one, I suggest that you contact the seller and inquire about an exchange.
I was in a similar situation when my used SAM failed. My reasoning was that used SAM's were more than 15-years old at the time. (They are now in the 20+ year age range.) Electronic parts of that age - especially parts that are exposed to the environment of an engine compartment - are likely prone to failure. I decided to buy a new SAM and that seems to have worked for me.
I appreciate that the new SAM's are pricey and it's your money, not mine. If you shop around, you may be able to find a new SAM for around $250.
What are you thoughts on the ground BRN/YEL having a positive reading only with the kay on. Also I failed to mention that the cooling fan is not coming on when the ac is turned on.
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