I have just purchased my first Mercedes, and I _love_ this car. It's not perfect though. I live in the south where it gets nice and toasty in the summer. The AC on this car only seems to work when I can drive ~ 45MPH or higher for at least two minutes at a stretch. I can feel it start getting cold, but then if I have to stop, the air turns warm again. The only time the car is truly cool is when I'm on the highway and can keep a consistant speed.

I found this extremely helpful diagnostic page, http://www.eclassbenz.com/node/27 and after following the instructions and collecting the sensor information & error codes (Error B1232 - Refridgerant Pressure Sensor Malfunction), it gave me some useful information:

Code B1232 Explanation: This sensor measures the pressure of the refrigerant in the A/C system. It appears to be malfunctioning. If this sensor is defective, you may be able to turn your A/C back on by overriding it.

The only problem is... it doesn't say how I can override it! My google queries came up shy of any useful information. Does anyone here have any helpful suggestions?

 

Hi,
The pressure sensor is there as a safety device for people and the system itself.
The A/C works under high pressure (circa 20 bar) and if for some reason pressure excess the design level of the system you could end up with a VERY expensive repair. If the switch is faulty replace it.
I THINK the switch provides continuity between a low pressure (about 6 bar) and a high pressure (guess 20 bar?).
You need to determine the characteristics of the switch but more importantly what is the pressure in the system?
Maybe the switch is OK and the problem is that there isn't enough refrigerant in the system. Maybe there is too much!
Checking the system pressure should be straightforward quick job for any A/C repair station.
Stuart

 

if the condenser temp is too high, the refrigirant pressure is high also.

see if the auxilliary fan is working.

spray good pressure of water on condenser to improve it's cooling function and see if the a/c cools while doing it.

 

yup check your auxillary fans for opperation you also need to check your ac pressures if your ac is low on charge the same thing will happen.