My little ZS has a issue with the A/C as soon as its turned on I hear a loud clicking sound which i'm told does happen, when I attach a gauge to the A/C to check levels of gas the gauge rises into the green area then drops off to zero then raises again to green and does this every 7 seconds and is not cooling the system at all, its like its recharging then pressure is lost so it starts recharging again whats the likely cause and how to fix the git or is it just low on gas so wont kick in ?