Air horn

I recently installed Hella Air horns on my CLK. The horns worked fine for three days, then all of a sudden nothing! At first I thought I might have mounted the air compressor somewhere that was too hot, and thought that is what was wrong. To check if it was the air horn itself or something electrical, I connected the stock horns back. After connecting the stocks, I tested the horn, and still nothing. When I press the steering wheel down, I hear a clicking sound coming from the fuse box, so I look in there to see if the fuse is burnt. Looking at the chart I couldn't find a fuse for the horn. Any suggestions on what to do, or does someone know which fuse is for the horn on the CLK.

Thanks.