I just replaced the belt tensioner on my 89 190E with 2.6 engine w/AC because I was told by an air conditioning repair shop that was the reason my air is not working. I understand there is a sensor that kicks off the compressor if there is a 15% difference in rpm's between the motor and compressor. I put on a new belt tensioner and adjusting rod but do not know how far to tighten the tensioner. I put on a new pointer and set it to the low end of the wedge shaped scale and tightened it to half way. I read where the tension should be set to the seventh mark on the belt tensioner for cars with AC but mine is a wedge. My question is how far up the wedge shaped scale should I tighten the pointer to?? My air is still not working with the pointer set at half the wedge scale. Thanks in advance. I hope I listed enough information for some advice.