Is the gas smell inside the fridge or the freezer?
both freezer and Fridge
Ok bit strange for both to smell of gas as each the fridge and freezer has its
own evaporator so sometimes you can get one fail and leak but the smell usually is in the one which has failed I cannot see both have failed so the smell of gas may have drifted through from one side to the other.
So as the gas has escaped the compressor will have been pump with no gas in there so it over heats and cuts out and this is when you get the clicking noise which you are hearing.
Im afraid for this you need to get a fridge engineer in as this isn't a diy fix. He will need to put there gauges on the pipe work at the back and put gas in there so they can find were its leaking from.
Fingers crossed its just a solder joint which can happen so they can redo that joint and regas it back up and sort it.
If its from the evaporator itself then it will need to be replaced and regassed.
Now for a regas you are looking at about £140 roughly but if it needs an evaporator or even compressor then its about the £200-300 mark.
If you need anymore info just get back to me.