Hello,
I have Dodge Grand Caravan 2013. And as I understand I have unusual failure (unusual sound coming from vehicle rear then AC is on). I brought my car maybe in 10 car services and no one can find that’s wrong.
I will try to describe this failure.
This unusual sound coming from rear then ac is on (I attached files with recorded sounds). If turning off rear ac still this sound coming. Only then turning off ac at all sound gone. But this sound coming then engine is fully in working condition I mean reaches normal working temperature. Then engine is cold and ac on working perfectly without these strange sounds then engine reaches normal working temperature starting coming these sound from rear.
Another strange thing these sounds coming then car is standing if you push acceleration pedal sound gone. And if you are driving on the highway also this sound is not coming out. By the way ac system do not have leaks. Holding pressure. Ac working fine during summer giving cold air in winter giving hot air. Also another point to mention then in system was very low Freon this sound was gone. But appeared another one very loud hissing/fizzing sound.
Maybe someone from you had such case?

recorded sound you can find in this wetransfer link