delayed start for my ac?

i have a 2010 honda insight, about 180k miles. within the past couple months i've had an issue with the ac and the heat taking 5+ minutes to turn on. it's strange because it isn't every time i start the car. sometimes the car starts the air as soon as i push the button and sometimes it doesn't. both the heat and the cold air are the correct temperature when it finally comes on. i can't find anything on this specific issue because it's both the ac and the heater. any ideas as to what this issue could be and how to resolve it?