Finally back home so decided to explore the insertion of a new Thermistor in my Waeco CF50-AC Version 8.
After nearly destroying the base of the cabinet, without any chance of removing it, I happened to pull on the Thermistor wire, and lo and behold, it just slid out of the foam.
Being curious, I cut a small hole in the base where I estimated the thermistor would sit, and found that in this model, there is a copper tube soldered into the unit. The thermistor is covered in white thermal grease.
It would seem this is a really simple job to replace, however the Waeco thermistor I had bought was in a black cover which was thicker than the original. Just a small trap to watch out for. I'm going to cut off the cover, and replace with heat shrink. Hopefully it will then be small enough to insert. I guess it needs the cover to ensure the thermistor ends up in the correct place. I'll
If you don't succeed & I don't know what you paid for the thermistor. But these look like the type in your picture. They are on Ebay for $3.00 with free freight, its a W1209 electronic thermostat which I have been using. But at that price its cheep just for a 10K ohm thermistor which is what Waeco use.
These are supposed to be genuine Waeco thermistors.
The interesting thing is that the one at the top of the first photo is the original. It has been fitted by sliding it up a plastic tube, into thermal grease, which is in that copper pipe firmly attached to the bottom.
The second photo, not clear, I apologise, shows the end of the white plastic tube into which the thermistor slides. Nothing I have seen on the forums shows this type of construction. Seems like a good idea if a new one can simply be fed into the tube with thermal grease. That's my next trial.
I did buy two genuine Waeco thermistors, intending to put them both into place, but the size of the tube precludes that job.
Its rather interesting the position of the sensor, as it appears to sense the temp of the plasic floor. Where previously they sensed the Evaporator temp.
Yes, it's new to me, not that I'm even a part expert on these. I'm guessing it's an attempt to make the repair easier. Should be good money for anyone doing repairs on this model, if they can get the correct size thermistor.
It would be easier to just stick the thermistor in the bottom of the fridge. My daughter has a 45ft yacht in Cairns & the mechanical thermostat was playing up on the built in Chest Fridge. So I made up an electronic thermostat using the $3 module & sent it up to her & she fitted it & just dangled the thermistor in the fridge & it works great. The fridge uses a Danfoss compressor.
The thermistor I received was a Waeco, but possibly a different model. The outer cover was too big so I replaced it with some heat shrink to stiffen it up. Slid the new thermistor up the tube with a couple of grams of thermal grease. Hooked it up to the control panel, and tried it with 240V. Freezer runs OK, but the display is about 10 degrees out according to the thermometer I put inside the fridge I can live with that so long as it's consistent. Anyway I have a unit which is now working.
Settled that down and tried the 12 V. Same problem as before. Would not stay on regardless of which cord I used. I then removed the 2 pin socket and attached the wires to an Anderson plug. Hooked it up to a battery and it's been working for 24 hours. Still not a correct temp on the display, but again I can live with it. Better than my other option of dumping the whole thing..
Interesting the temp is 10 deg out. The $3 thermostat ive show can be programed from -7 to+7 deg compensation to allow for discrepancies. But its good that you have salvaged the fridge & its working again. Ive found with Waecos the electronics is generaly the weak part of there design. Also I have wired my 12V dc to the back of the 2pin conector & used heavier flexible cable, as the original lead is not very heavy.
I agree that the electronics in Waeco leave something to be desired. Case is OK as is the Danfoss, pity about the rest.
I'm still doing testing relative to the display. Set it to 0 degrees or above and it is not far out, going into freezer temps is where it is most different. This is on the 12 V. When I've got that sorted I'll have a play with 240.
I only want it as a bait freezer, so am not too concerned so long as it doesn't just give up the ghost at a bad time.
