Calks

Hi All. I have a MKll 1.9 tdi Galaxy with a strange problem. I had the famous flashing control panel on my DATC unit and after diagnosis with IDS it pointed me to a re-gas. I took it to a reputable garage who charged me

They recovered 115 and refilled with 750 + 10 UV

I have a MKII 1.9 tdi 51 plate Ghia. I have been having problems with the air con. I have checked out the system with IDS and found a fault code relating to the Dual Pressure Switch. I replaced the switch. I have now had the whole system Vac & Filled. I checked the pipes under the bonnet after starting the car. One is cold the other hot. Cold air is blowing into the car. But!!!! this only lasts for about 2 minutes at the most and then the system reverts to no Air Con. My problem is that the compressor only activates for the first minute or two after key on & start. If I shut down the engine and ignition and restart the whole process starts again. IDS is showing no faults. Can anyone advise??