Thanks again for your reply.
I removed the left fender trim in the trunk to see the oil level in the expansion tank.
With the hood closed, the level is approximately 3 cm below the minimum level mark.
I think as you say, that the problem can come from this lack of oil.
I ordered PENTOSIN CHF 11S oil recommended by MOPAR and a syringe to fill the reservoir.
I'll let you know the result.
Thanks