2000 Pajero Air Con Compressor Relay

We've been having issues with our 2000 Pajero Air con. Compressor replaced under warranty. Now the air con starts up and is nice and cold but after 5 - 10 mins of driving the cold disappears and we just get outside temp air coming through. I've checked a few things and thought it might be the Compressor relay gets hot and cuts out. I looked in the fuse area and found two relays with snow flake symbols. Anyone able to help me with working out which one to replace?