The weather turned warmer, tried the A/C today and no cooling. So I checked the trouble codes in the HVAC control and had one...416-coolant circulation pump. I checked the pump (I assume this means the small elec. one) and it's fine. Thinking it could be an old code I deleted it and it hasn't come back.

Here are the values from the A/C control module:
1 - 76
2 - 70
3 - 124
4 - 96
5 - 71
6 - 156
7 - 40
8 - 68
9 - 0
10 - 1.7
11 - 1.7
12 - 4.2
20 - 0
21 - 7
22 - 0
23 - 0
24 - 14.1
40 - 2
41 - 3
42 - 1
43 - 130

I don't have a pressure guage to measure refrigerant pressure, and there is no sight glass, but thought value #7 at 40 bar indicates a high pressure.

All fuses checked OK. But I see the aux fans don't run when A/C is on. The compressor turns.

Any clues as to what to look for next?

Would you be willing to share with us what year and model you are working on? Is it a Mercedes?

Thanks,

Its a '96 S420, W140.