A few things here:
If you disconnect the gas supply to a fitted appliance - like the fridge - the gas connection should be remade by a competent person.
If the fridge works OK on the workbench, but not in the caravan - it means that the problem is caused by the location and fitting of the fridge, because the air flow providing the cooling is not good enough.
When the fridge is fitted in the caravan it's quite important that the back of the fridge is sealed from the caravan interior, so that cooling air can only flow in the bottom vent and out the top vent - and nowhere else.
So it makes a sort of chimney forcing air to flow correctly. And also if you use it on gas, that the flue gases vent outside the caravan.
It's also important that the air space behind the fridge and the caravan wall is quite small - so that air is forced to flow past the heat exchanger and cooling fins - like up a chimney.
You may also want to look at the aluminium deflector plate fitted above the heat exchanger and cooling fins - this should direct hot air out the top vent.
Robert
And if you can't get the air flow right, call out a mobile fitter.