Dometic RM2852 not cooling

[another_newfie]

On our annual NYE camping trip my trusty Dometic RM2852 fridge has experienced some sort of an issue. The fridge worked fine on the first night but by the morning it was obvious something was wrong. It is no cooling on either electric of LP. In fact the absorber vessel was ice cold. No signs of any leakage, no ammonia smell. Fuses all test just fine.

The fridge indicator lights behave themselves and starting the fridge on battery only with 120 completely unplugged from the rig, the indicator lights come on an LP flame lights. Appears completely normal. Waiting for many hours like this produces no cooling whatsoever. If I apply electricity to the rig the fridge kicks over to electric and LP flame extinguishes. I am taking a leap here and thinking that the circuit board is likely alive because of this behavior.

Maybe a bad thermistor or worst case a failed cooling unit.

One thing to note here is that I did 'bump' a tree pretty hard on the back in to the site (the joys of winter camping and backing through a snowbank), so I was thinking there is a chance something may have jarred loose and is blocking ventilation? Somewhat unlikely since the fridge did appear to cool normally the first night.

Any thoughts are greatly appreciated. The fridge is only 3.5 years old and the rig gets used very regularly, with at most 3 weeks or so between trips.

[5picker]

If the chimney gets hot (from either the propane flame or the 120v element) but the evaporator fins inside do not get cold (nor do the condensing coils at the top outside get hot) then either the ammonia has escaped or there is a blockage that is not allowing the ammonia to evaporate and condense which provides the cooling action.