1999 Chevy Monte Carlo Car smells of coolant when running

Once the car gets hot you can smell coolant. Please note that the gauge indicates the tempature is normal. You can smell the coolant inside and outside the car. No leaks are evident.

Also, when the air conditioning is turn on, one vent will blow cold air and the other hot air. Sometimes both vents will blow cold air and sometimes they will both blow hot air.

Any advice is appreciated.