Thetford

A gas absorption fridge uses a heating element to boil and circulate the ammonia solution. This solution condenses and in doing so, absorbs the heat from the fridge compartment, hence the name.

When an element fails, this cycle cannot happen and the fridge will not function. It will still operate on gas and the 'other' electricity source (be that AC or 12V). With the exception of the "manual" R1G models, all Thetford fridges will show a fault code to signify an element has failed. Technically, the fault code is reporting the element is not drawing enough current, but the likely cause of this is the element failing open circuit.

The fault code shown will be a code 8 (R3G and R4G models), or code 1 (R2G models). Element failure on an "manual" R1G fridge will appear as the fridge being "dead" on AC but working OK on 12V and gas. Early N145 LED models will indicate a fault by the LED flashing in a certain sequence.

To test an element, we need to measure the resistance between across the heating element wires and compare it to the values below. In the majority of cases, an element will fail "open circuit", meaning the continuity across it has broken, or it will fail as a dead short. An element is a device that will either perform 100% or it won't work at all, so it's not possible for an element to be "failing", "degrading" or be "on it's way out".

The video below shows how to test the AC element on an N3112. The basic method is the same for all Thetford fridges.

The resistance values vary depending on the wattage of the element but should be as follows:

In some cases, especially with 230V versions, an element failure can result in a blown fuse on the fridge PCB so it's worth checking this too.

Thanks

Rich