AC problem

[jjrodger]

I think I have a problem with the AC on my 1999 R129 SL500.

It runs fine in "EC" (Economy) mode, ie without AC. However if I turn the AC on, the air supply dies after about 10 to 15 mins. The fan speed increases (as the sensors detect the increasing interior temperature), but no air comes out of the vents. This happens even if I override the "Auto" setting and turn the fan up to max and demand air from the vents: still no air blows (although the fan makes a noise). The problem is temporarily cured by switching back to "EC" mode for a few minutes; the air then blows strong again. However, this means regular fiddling with the aircon controls.

As summer approaches I'd like to put this right. I'd appreciate your input before going to the dealer...