Waeco

Thanks Allan,
From memory that brand has 3 different 10k ntc thermistors, all 10k at 25 degrees but have different coefficients. The chart you have referenced is the same as the sensor that come with my controller but I am unsure if it is what Waeco uses.
If I could get confirmation that it is the same Id rather buy a waeco one next time because they last a lot longer than the 6 to 12 months the ebay ones seem to last.
Hence the reason I am making it quick change at the expense of a small reduction in insulation efficiency.

.
Ah yes, I see what you are saying.
At the time of modifying my Waeco I needed to experiment to determine the value of resistors I needed for the set point (which were not the same ohmic values as the sensing thermistor) so I ran the fridge to the desired temperature by a thermometer then adjusted the ohmic value of my resistor to achieve cut-in/cut-out of the motor. Don't think I recorded the resistor values.

It surprises me to read of the many Waeco thermistor failures…… other brands are not so reported. A thermistor is a simple and electrically unstressed device and easy to manufacture to be water resistant. If I were to be fitting a Waeco replacement I would maker sure that I made it waterproof. Smother it with silicon or the like. I have not had reason to inspect the Waeco arrangement…… are the sensors encapsulated or is the thermistor bead exposed to the environment?

They look just like the cheapies on ebay, about 20mm of stainless sealed with some form of epoxy and about half a metre of small gauge figure8 and a 2 pin socket.
The one I changed on my CFX is located in a tube, i put about an inch of heatsink compound in a drinking straw and pushed it to the end and blew it out of the straw, then pushed the sensor in till I felt the compound squishing around it, works well.

The CF is a different story. Utube clips showing them wrestling the cover off brutally to dig through the insulation to find the sensor in its little clip.
Way too hard for me, i just cut a 2 inch square in the bottom of the case but missed, the sensor wasnt where the Utubers said it was so the old one is still in there somewhere, and just attached the new one to the bottom of the fridge compartment floor in a 6B&S eye terminal, not the prettiest but it worked.
This time I have included a Bic biro case from the outside of the case so next time it can just be changed without taking any covers off.

.
I am familiar with the type you referenced..... there is one on my bench right now, connected to a thermostatic display/controller. The 20mm stainless is essentially a thermowell with some sealant where the insulated wires exit. An effective seal requires the sealant to fill the void where the bare wires connect to the element in order to avoid moisture migrating along the wire path inside the cable insulation. This requires some care not always applied to consumer products.

It will eventually come to that Im sure, but the new one will be going in the ute and my once new but now 10 year old CFX will end up next to the spa.
Not sure what affect the water full of chemicals and the very humid (sometimes steamy) conditions will have on a fridge over time so will stick with experimenting.
A 20 dollar controller and a couple of 3 dollar sensors is still a lot cheaper than a cheap fridge.

I’m in my spa most days, but usually it’s only long enough for one beer. !!

Yes Gronk, there is one other limiting factor but I can usually last 3 beers.
There is a sewer inspection cover in the slab next to the spa too, but swambo wont let me do the plumbing for that, something about it not being fair for the girls lol.