2017 Elantra. Everything was fine. Just recently I had to fold the drive side mirror up few days ago. And today I realize that I cannot fully control that mirror from the switch anymore.
It can be moved up and down but it won't move left and right. There is no motor sound when I try to move it left and right.
I tried looking inside the mirror from as much as I can see from the outside and seems like that all connectors are connected fine. I'm assuming there is only one motor for all four directions? If so then it can't be a bad motor.
The siwtch inside is fine because I can fully control the passenger side mirror.

 

Don't know for sure without looking at it, but there is a good possibility the wire that controls the left to right movement may be broken so the signal to move it is not getting to the motor.

 

From what I've researched, there isn't a way to open the back of thekrror or anything. Do you know how I could get inside the mirror housing? I think I can easily remove the whole mirror from the car though.

 

Pretty sure you will need to remove the door panel covering to do this, but while in there you might verify power from the switch for that position selection is getting to the mirror.
There may be a flaw in your deduction, however, and that is there is another switch that sends power to one side at a time.
You have to start at the switch with the correct side chosen and verify from there.

 

Don't think switch is the issue as the mirror can move up and down. Just doesn't move left and right.

 

Man I'm confused. So I removed the mirror glass, disconnected and reconnereconnectd the motor wires.
still, the motor only moves up and down, not left and right.
Unless the motor has different servos for the up/down and left/right movements?
It can't be switch inside the car because I can control the passenger side mirror just fine.

Ideas?