My aircon is not working. On a hot day, it only blows cool air and not cold air. I have run the diagnostics and come up with a code 15 which suggests the refrigerant temperature sensor is open circuited. But I am also concerned that I may be low on refrigerant. Would this be an alternative? If the problem is the refrigerant temperature sensor, can I replace it without draining the aircon system? Any idea of a part number? The car is a JDM in the UK.