Hi all,

I have a 2000 C280 with the digital climate controller. My problem is that, after driving on the freeway for more than about 5 minutes, the A/C stops blowing cold air. Using diagnostics in the CCU, I see that sensor 07 (refrigerant pressure) reads LO for as long as freeway speed is maintained.

As soon as the car is stopped, the A/C compressor engages, sensor 07 reads in the range of about 5-20 bar, depending on speed and temperature, and the system blows icy cold air.

Does anyone have ideas on what is going on here?

Thanks.

 

Hello again,

Does anyone know what would cause the A/C compressor engage normally when the car is stopped, but not engage while cruising at a steady speed?

 

It might be the A/C clutch silenoid. My C240 was doing that until it stopped working all together. It ended up being the compressor and dryer. $1300 out of my pocket!