Your hinges could potentially become loose after a while. If this happens, your doors will look as if they are sagging when they are open. Have a look to see if you have loose hinges or if the screws are coming loose. You may also need to remove the hinges and set some wood dowels in the screw holes. 

Occasionally, you may find that your latches are not working the way they are supposed to. Your door should be properly lined up to the latch when closed, or you may need to reposition it. If your doors are not staying latched once you have closed them, it’s a sign you may need to line things up again. 

Air in your home can be lost through a crack in your doors if one appears after a period of time. Weather stripping has usually been worn away at this point. All you have to do is replace it with a new piece. 

Both types of door handles used on patio doors, the small latch kind that you press and the kind that you twist can stick, and this can cause your doors to malfunction. This can be due to a build up inside of the door handle. Using WD-40 lubrication can help you to clean out any debris and grime that is stuck in there. 

This can be down to a structural problem with the door frame. Removing the trim and placing some shims in to level the door frame can work. However, removing the frame may be necessary if this does not work. 

By maintaining your patio doors well, you should experience less troubleshooting issues. Your maintenance routine should include washing the doors, cleaning the hinges, tightening the door handles, and making sure all the working parts are in good condition. Doing these things regularly should help you to avoid major issues and ensure your doors stand the test of time. If you experience an issue with your patio doors and you’re unsure of how to proceed, it’s always best to call a professional to avoid more damage in the long run!