A quick check is to switch on the air con and fan then check that the clutch on the front of the comressor has pulled in (it should click in and drop out when you switch the a/c on and off). If the clutch pulls in and drives the comressor then check at the front (right)of the vehicle in the pipe going to the condensor radiator, there is a sight glass clean it and check that it is clear, if tiny bubbles are flowing through it there is air in the sytem and it will require a top up charge. If the compressor clutch is not engaging there is three possibilities 1. it has lost all the gas and will not start due to low pressure (requires locating and fixing leak and complete vac and recharge 2. there is a fault with the compressor clutch( check by disconnecting the connector at the clutch and run a jump wire to the battery positive terminal when you touch the two together the clutch should pull in if it doesn't the clutch has a problem) 3. there is an electrical problem in the control cct get it checked. :drink1: