'07 E320 code-9205 B12/2 refrigerant pressure sensor - PeachParts Mercedes-Benz Forum

ROLLGUY · #1 12-14-2017, 11:08 PM

I am trying to get my A/C to work on my '07 E320 Bluetec. Before the collision, the A/C worked flawlessly. After replacing the condenser/drier, I had it charged. The compressor would not turn on, and the red light would blink on the A/C switch. I checked for DTC's in the system, and got the 9205 code. "Refrigerant pressure too low. check refrigerant level. B12/2 (refrigerant pressure and temperature sensor)". I had the refrigerant removed, and replaced the switch. I then had it charged again, and the same code came up. I checked the wiring, and it is intact. I also checked the fuses in the front SAM, and they are all good. I also have no idea what fuse is for what, as the only listing is for the fuse panel to the left of the steering wheel, and in the trunk. I am not sure what to do next. If this was a 123, I would have no problem troubleshooting this problem. This chassis is much more complicated than a 123! Any help would be greatly appreciated. Thanks, Rich

97 SL320 · #2 12-15-2017, 08:10 AM

Are you able to see the pressure on the scan tool or pull it up in the AC control like the older ones?

The pressure sensor is probably a 3 wire unit. Power in , ground , signal out. If two wire it will be a variable resistor.

Most thread on pressure switches can be changed without discharging the system, there is a valve in the port.

From what I recall on the 90's cars, the pressure SW and temp sensor are two units, is this the same on yours?

ROLLGUY · #3 12-15-2017, 10:27 AM

Quote:

Originally Posted by 97 SL320

Are you able to see the pressure on the scan tool or pull it up in the AC control like the older ones?

The pressure sensor is probably a 3 wire unit. Power in , ground , signal out. If two wire it will be a variable resistor.

Most thread on pressure switches can be changed without discharging the system, there is a valve in the port.

From what I recall on the 90's cars, the pressure SW and temp sensor are two units, is this the same on yours?

Yes it is a 3 wire switch, and no there is not a valve in the port. I checked and there is +5v on the red wire, and the brown (ground) is good. I am not sure about how to use the scan tool for reading the pressure, but I can connect it and search each menu for something. I am still learning about the MB II.

jay_bob · #4 12-15-2017, 12:34 PM

I think it may be a latching fault and you may have to clear codes once you’ve established a proper charge to get the fault to clear. The 210 is like this, although the 210 can clear climate codes from the CCU. Not sure on the 211 since they went to a non-display CCU.