Hello ya'll.  I have a 2018 Honda Civic Hatch EX with 29,949 miles on her (bought new).  Recently, whenever I get in my car after, after its been off for hours, and I smell a sweet chemical like smell.  When the car is powered on, the smell does dissipate at a decent rate.  I assumed it was a coolant leak somewhere in the cabin, so I took her into the dealer and told them what I've noticed.  They took her in for over an hour.  They said they used some tool where they us UV light to check for any leaks.  Nothing.  I asked about a possible leakage in the heater core, they said, no signs of burnt or cooked coolant there.  I also asked if the coolant levels where normal.  They were.  So no luck.  The smell is still there and only present when the car is off for hours and the engine has mostly cooled.  I tried turning the A/C on full with the windows down and drove up a hill fast to test if the car temp gauge fluctuates.  It did move up one little notch when running it hard, but when I drove normally with A/C off.  The temp returned to normal.  So now, I'm not sure it is a coolant leak.  I was reading that it might be the A/C since some car Freon can have a sweet aroma.  But my A/C was extremely cold when on (it could be small leak though).  I'm just confused right now.  Any insight would be helpful! Thanks!