Check your fan is working using the demister test, aircon off, press the demist button, the low speed fan should kick in and run continuously. If it starts and stops there's a problem, cause varies depending on what type of fan you have.
Re ejecting coolant, how much coolant are you putting in? "I syringed about 300mml out to just reveal the ribs.", that's way too high. The max level is right at the bottom of the tank. If the tank is overfilled the excess will be spat out. You can see the max and min levels at the bottom of the tank in the pic below.
