Today, about 5 minutes after leaving the house I hear a ding, and I see the temp needle is in red.  It didn't stay there, as it soon went down to 3/4.  Normally the needle is pretty much dead on in the middle.  The needle stayed 3/4 during the evening, sometimes going down.  I never heard another ding, and it never went close to red again.  Our van is a 2017 Dodge Caravan SXT with 180000 miles.  Any suggestions on quickly resolving this to ensure a safe trip.

Also, the last couple weeks or so, my AC will intermittently drop in fan speed and I lose coldness.  This will happen a few times, eventually tapering off.  

Could these be related?  

Thank you.