Battery voltage drops

I assume that when you notice the lights flicker is when the A/C is kicking on and off. This is going to be the same time you see the voltage drop.

I suspect the compressor or compressor clutch may be starting to lock up and when it kicks on it literally slows the engine or bogs it down and this will slow the drive belt which will slow the alternator for a split second. This will cause all other electrical loads to be effected which is why the lights are flickering. Further evidence is this doesn't happen with the A/C off.

Unfortunately we don't have a manual on your vehicle but here is a guide on how to replace a compressor.

If it were me, I would do this and then retest it. Based on this information, I am not sure what else could be the cause.

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Let me know what you find and we can go from there. Thanks

Okay. The compressor may be operating properly but you are experiencing an issue when this is kicking on and no issue when it is not on. So while it may be operating it seems to cause this issue. How long have you owned this vehicle? Has it just started doing this or if you just bought it this may be normal for it.

Maybe get a video of what it is doing so we can see the issue. Thanks

You can do that. It won't hurt. Again, I am not suggesting it is the compressor is faulty or the alternator. What I am saying is that when the compressor kicks on, it actually slows the engine which causes the alternator to slow due to the belt not spinning as fast which will cause a voltage drop. Clearly we have a load issue due to this only happening when the A/C is on. This is what would make the most sense.