Thetford fridge

Since someone attempted to steal the motorhome it’s now parked the other way around on the drive. I switched the fridge on a few days ago, it initially cooled down and I put a few bits in the freezer box whilst we defrosted the freezer in the house. Job done I went out the the motorhome and found the fridge had failed to stay cool. It was operating on mains. I tried a few things, gas. Switched it off and back on put it back on mains and left it for an hour.
It appears to be trying to work, but if you put your ear to the vent outside, I can here a faint hissing and bubbling noise?
The only thing I can think is the drive and the tendency for the motorhome to sit nose down have both contributed to the fridge being out of level.
I plan to turn the motorhome around  which will level it and try again, has anyone  experience of anything similar? 

Thank you all again in advance.

Same model fridge in my van, have tried several different ways to get it to perform effectively and consistently, all unsuccessfully. I now use a separate cool box and use the fridge as a shoe locker, though it is not a lot of good as that.

I'm horrified! I have a Thetford fridge, generally run it on 4 bars (out of 5) and it cools very well. However, the ice box is just that - it's not meant to go to -18C, home freezer temperature. That means that ice cream is not solid but neither is it runny. Frozen food will keep for a few weeks but I wouldn't expect it to keep for months as it would at -18C

Since we moved to our new place, which has a steeper driveway than the old house, the Thetford fridge will no longer work on the driveway.
As soon as the van is parked somewhere less steep, it works fine.

My fridge now works again once the motorhome is level, I was concerned as the noises it made when it went wrong, but all appears well.

Hola! My fairford sits nose down on our drive. I’ve stopped cooling fridge overnight before a trip as it wasn’t cooling. On day of departure I just fill it anyway, fill the freezer with already frozen stuff and drive off with it on 12 v......it’s all fine , food is still frozen, still fresh and we could have been on the road for 4 hours before arriving at a site and everything works.

Have seen a figure of 3 degrees, which really isn't much.
Mine on dead level launch pad is 3 degrees nose down even then.
Fridge does work though

Inspired by IanH's post, I thought I'd measure the slope of ours.
My Nuevo, with the Thetford fridge, sits on a drive which slopes forward by 3.8 degrees. The fridge works normally.

Cymro