i think your thermostat valve is not working properly.
its a small part which is responsible for the water circulation and allowing cold water from the radiator to go in the engine for cooling.
usually water inside the car takes around 15-20 minutes to properly heat up and that is when thermostat valve open up to allow cold water to replace the hot one in engine.
just verify 2 things. 1 your radiator and AC fan are working fine.
Your thermostat valve is working fine.
let us know hopefully issue will be fixed. i don't think u should be opening up the gas kit at this stage.