HI ALL, I AM HAVING THE SAME PROBLEM WITH MY LATIO. Same light hissing sound then i went to tan chong ubi to service, they top up the gas and become cold again only for two days. Then start blowing hot air again. my latio 3years 10 months. Guess around 4years latio will start having this problem. The ******** tan chong mechanic cant find a reason for the hissing sound and tell me to change the whole aircon unit for $2.4k..faintz..