1980 240D AC replacement
 

I have purchased a 1980 240D and it has become my labor of enjoyment. I am going to replace the AC compressor, AC drier, pressure switch, and expansion valve. This model takes GM radial R4 compressor. I know this may sound elementry but how do you loosen the drive belt? I am use to seeing a pivot bolt and slide channel. Any do's and don'ts when doing a project like this? Do I have the system flushed before or after installing the new parts and charging?

The whole compressor rotates like an alternator. Look on the back side for three big bolts.

Thank You Steve...any other insights into the do's and don'ts of this project ?