My 2014 CX-9 has a strange knock coming from the drivers side. Almost like somebody hit the car with a rock.

It usually occurs toward the back seat area, occasionally toward the front. The loud knock occurs randomly. Sometime VERY loud, sometimes not so loud. Usually when the car is moving, but sometimes when at a dead stop with the engine running.

This has been going on for about three months now.

My mechanic checked it out but didn't hear the sound. However, he confirmed the car is driving well.

Has anybody ever experienced this? It's driving me crazy and I'm about ready to sell the car.

Thanks in advance for any ideas.

 

With or without the A/C going?

 

I don't think it happens with the A/C on, but definitely with the heater and fan running.

Two more clues:
A few coins that were in the front door pocket slipped behind the door panel. For a while we heard them rolling back and forth inside, but we don't hear them anymore.

A few years ago the front driver's window would open on it's own after we parked the car and walked away. The Mazda dealership fixed it, explaining something in the lock mechanism (I think) became disconnected.