Coolant gauge temperature
 

My problem is when the outdoor temperature is above 60 F the coolant temperature gauge holds dead center. When it's below 50 F the gauge drops to the cold blue bar---strange. I'm not sure if its the thermostat or temperature switch. Anyone ever have the same problem?

Could be the thermostat. When was the last time you changed it? Double check the coolant level and bleed the cooling system in case their is air in the system.