1. Remove the rear door trim.
2. Remove the screw and bolt, then remove the glass guide.

3. Remove the quarter window and the molding together in one piece.
4. Remove the molding from the glass.
5. Install in the reverse order of removal.
Windshield installation
Rear window glass removalMazda 6 Service Manual: No.8 no cool air
When performing an asterisked (*) troubleshooting inspection, shake the
wiring harness and connectors while performing the inspection to discover
whether poor contact points are the cause of any intermittent malfunctions.
If there is a problem, check to make sure connectors, terminals ...
Mazda 6 Service Manual: Instrument cluster removal/installation
Caution
When replacing the instrument cluster, the configuration procedure must be
performed before removing the instrument cluster. If the configuration procedure
is not performed before removing the instrument cluster, it is possible that the
instrument cluster will not operate normally. ...