error code
1231 = engine coolant sensor
1233 = refrigerant temperature sensor (on dryer)
1419 = magnet clutch on compressor
1421 = pulse module (fan speed control relay (under right headlight)
1424 = charcoal filter flap stuck open
Firstly half cooling as you are facing is a classic sign of low refrigerant in this car - this happens as half the A/C evaporator is chilled while the other half is not chilled hence 2 vents blow cold while 2 blow warm. The engine coolant sensor and refrigerant temperature sensor could have been triggered by someone fooling around with them, The charcoal filter flaps can be a genuine fault or some A/C technician breaking it off (can happen if inexperienced people service this car)
firstly I would suggest you read the real time data, it can be achieved by switching on the system (press auto) and then press "REST" - it should start to show a number and its value on the screen, toggle between them with the left and right auto buttons. Note all of them and then erase all fault codes (get into fault retreival system again and press both auto buttons for 2 seconds after reading all fault codes) - this should get the system out of the stuck economy (EC) mode.
Start the A/C - the compressor should engage, if it does not then switch the unit off and proceed to test the compressor clutch wire signal. If you see battery voltage when activation is required then the system is good. You have a dead clutch. Mine had this too. my compressor's clutch went out and I replaced it.
Verify that the engine cooling fan runs when required, its run by a pulser relay, it can go bad if someone was overgenerous with water or if the splash panel under the bumper is completely missing.