Mr Zhao arrived our workshop with his Audi Q7 complaining for knocking sounds coming from under and is also having an air conditioning problem.
Issues do come in pairs. Mr Zhao hears knocking sounds coming from under his Audi Q7 wasn’t music to his ears. And another air conditioner problem left him chagrined. 
The faulty lower arm bushings attributed to the clunking sounds from under his car. 
The arm bushings are replaced in pairs. Each arm comprised of a pair of bushings, so both arms should have the bushings replaced simultaneously for equal balance. 
It is not feasible to repair the worn-out the compressor for the car air-conditioner. Better to replace a new one. 
Mr Zhao now enjoys a smooth, quiet drive on his Audi Q7.
