Waceo CF50 problem

Submitted: Friday, Nov 29, 2019 at 12:23
ThreadID: 139368 Views:884 Replies:6 FollowUps:7
My CF50 has ran with no problems for a couple of years but recently ill go to it and the temperature will be at 10 degrees, for instance. Even though it is set for 2 degrees. The green light is on and looks as if the fridge is running fine.

If I turn it off for a while then back it will start to cool down again.

Anyone witnessed this?
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Reply By: Frank P (NSW) - Friday, Nov 29, 2019 at 12:35

Friday, Nov 29, 2019 at 12:35
I had a random similar issue with a no-name Chinese fridge modified with a Danfoss BD-35 compressor, which I believe is what is in the Waeco. (The suspension in the original Chinese copy of the Danfoss, a Domus, failed, hence the upgrade.)

The problem turned out, after trial and error, to simply be a bad connection in the ribbon cable between the display circuit board and the main controller board (not the internal Danfoss one). Removing the ribbon, cleaning the connectors and re-installing fixed it.

Your problem may be something as simple as that.

If you're handy with tools it may be worthwhile carefully poking around a bit, checking for loose and dirty connections.
AnswerID: 628847

Reply By: RMD - Friday, Nov 29, 2019 at 12:44

Friday, Nov 29, 2019 at 12:44
Paul
Not sure if same fault, but I repaired one which had the NTC thermistor faulty. Some seem to fail and give wrong resistance reading to the comparator circuit on the board.
If you can open the circuit part and unplug the two wire cable going down into the insulation, it should measure around 10,000ohms when at 20C ambient, if not it may be faulty. Because they carry a minute current to detect the resistance, moisture and applied temp cause the junction of the NTC chip to not work well. I purchased a 10,000 ohm NTC resistor and soldered two wires to it which were then connected to same circuit contacts. The fridge then worked as required.
Using a very powerful LED light source shining into the base you can see where the sensing end is under the plastic liner at the bottom. Usually midway other end to compressor. Knowing that, I cut a ciggy packet sized square out of the case base to access the faulty sensor. On the wire, I cut off the old sensor and after attaching the new one with wires now attached, all was securely sealed and glued to underside of plastic liner. Fridge now has worked properly for two years. The void I carved in the case was filled with expanding foam and the cut out case bit simply soldering iron welded/plastic welded to repair that cut out. There are a few faults happen with them, this is only one of those. Hope you find it.
AnswerID: 628848

Reply By: Batt's - Friday, Nov 29, 2019 at 17:53

Friday, Nov 29, 2019 at 17:53
Not long ago my CDF11 started to get temp changes usually have it set around 2 or 3 deg it went into the minus region around -5, -7 deg etc rang the local repairer he was pretty honest said it would cost a bit just to diagnose the issue so recommended replacing the thermistor found one for $30 swapped it out it works fine now you can get them cheaper. It may be your issue not sure.
AnswerID: 628851

Reply By: HKB Electronics - Friday, Nov 29, 2019 at 20:42

Friday, Nov 29, 2019 at 20:42
What I have found, first off suspect a power problem to the fridge, ie faulty lead or plug etc.

If power ok then most problems seem to be caused by either the temperature sensor as written above, or the voltage regulator.

In my particular unit though it turned out to be the processor PCB, on initial turn on compressor would run for some time and cool down the fridge, then cycle on and off rapidly, temperature control had little affect,
turning it down would result in compressor running for a short time then going back to rapid cycling.
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AnswerID: 628856

Reply By: Blown4by - Friday, Nov 29, 2019 at 23:49

Friday, Nov 29, 2019 at 23:49
If you do need to change the thermistor, you don't need to cut the plastic body of the fridge or remove the old one at all. Just leave the old one where it is and install a new one up against one of the condensor coils from the compressor end. If you ring Waeco in QLD and give them your fridge model they will give you the exact measurements where to dig out the foam and where to install the new thermistor with thermocouple paste (from Jaycar). You then back fill the hole you dug out with expanding foam and remove the two wires from the RS thermistor where they connect to the PCB and plug in the two wires from the new thermistor.
In my experience when the thermistor fails the digital read out indicates a higher temp than the actual fridge temperature and the big indicator is that the compressor just keeps running 24/7 even though the fridge is cold because the digital read out is telling it that it isn't cold.
AnswerID: 628861

Follow Up By: RMD - Saturday, Nov 30, 2019 at 09:00

Saturday, Nov 30, 2019 at 09:00
Blown4by
Probably the one I repaired was an earlier model but there was no way you could remove the thermistor from the other end, It was clamped securely into an aluminium plate attached to the underside of the liner. The thermistor isn't against the condenser, it is near the evaporator which gets cold. The condenser gets hot because it has to cool the compressed gas and only after the gas is cooled under pressure can it again be allowed to expand so it can accept heat from the surrounds.
My repair was, the compressor ran all the time, ie always freezing but digital temp reading was warm.
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Follow Up By: Allan B (Sunshine Coast) - Saturday, Nov 30, 2019 at 10:28

Saturday, Nov 30, 2019 at 10:28
.
Maybe Blown4by is confusing the terms "condensor" and "evaporator" but in any case it is not good practice to attach the sensor directly to a chilled section of the evaporator as this will result bin short cycling times.
This is the very reason that Waeco chose the location away from the evaporator.
Cheers
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Follow Up By: Blown4by - Saturday, Nov 30, 2019 at 13:16

Saturday, Nov 30, 2019 at 13:16
RMD: Yeah sorry mate I did confuse the condensor with the bit that gets cold. My point was that you don't need to remove the failed thermistor. You just leave it where it is and fit the new one in an easier to access location still up against the evaporator to sense its temperature. Mine is a CF-60 and it had exactly the same problem that you describe your had. It was Waeco technical ppl in QLD that told me to do it that way and that is what they tell there accredited refrigeration repairers to do otherwise you have to cut holes and just about wreck the fridge body assembly to get it apart. The new thermistor still receives the same temperature information from the evaporator coil but from a different location to that where the original one if located when the unit is built.
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Follow Up By: Blown4by - Saturday, Nov 30, 2019 at 13:34

Saturday, Nov 30, 2019 at 13:34
Allan B (Sunshine Coast): Yeah sorry mate I got the evap & condensor mixed up. Installing the replacement thermistor next to one of the coils in the evaporator plate is what Waeco technical ppl in QLD told me to do. I am just relaying here exactly what they told me and it is what they tell their accredited refrigeration repairers to do when they replace that part. The original location where the thermistor is installed at the factory during build is still adjacent to one of the evaporator coils sensing the same information as in the revised location, its just that you don't have to basically destroy the structural integrity of the fridge body to get to where it is to replace it. I was very glad I spoke to them as it made relatively easy, what I thought was going to be a mongrel of a job. CF-60 is now working great.
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Follow Up By: Allan B (Sunshine Coast) - Saturday, Nov 30, 2019 at 14:38

Saturday, Nov 30, 2019 at 14:38
.
Well Bb, I would need to ask the question... why do Waeco position the thermistor at the bottom when up on the evaporator will work anyway?
And why would Waeco instruct service technicians to put it on the evaporator? Maybe because it is an economic compromise? And why would Waeco care? After all, you have already bought the product. lol

It is not that hard to replace into the original location.... the internet is awash with instructions from blokes who have done just that. But if the easy way suits.... go for it. Just be aware that the thermistor will not indicate the representative temperature of the cabinet. The control point will need to be set lower in order to maintain the correct food temperature.

Cheers
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Reply By: Paul W33 - Saturday, Nov 30, 2019 at 15:08

Saturday, Nov 30, 2019 at 15:08
Thanks everyone

Should the fridge show the same problems if I plug into 240v. I have just got access to mains power (we travel full time) so I will see how it goes.

Cant say I'm all that confident doing what you have suggested but will look into it

Paul
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Follow Up By: Member - McLaren3030 - Sunday, Dec 01, 2019 at 07:57

Sunday, Dec 01, 2019 at 07:57
Hi Paul W33,

I am not a refrigerator mechanic, but I would think that if the issue is to do with the thermistor, it would be irrelevant if the fridge was being powered by 12 or 240 volt power, as the fault is not “power” related. Happy to be corrected, just my opinion.

Macca.
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Follow Up By: RMD - Sunday, Dec 01, 2019 at 12:04

Sunday, Dec 01, 2019 at 12:04
Paul.
Seeing you are travelling, for the interim, you could get a thermistor from Jaycar in a town, solder it to some thin wires, seal it with silicon and attach wire to the same spots as the OE sensor on the circuit board. That way you can then drop the thermistor into the fridge compartment and have it against the side not near the evaporator, (the cold bit) and it should then regulate the temp fairly well. That is how I checked the ones I have fitted. On the circuit board, there is usually a small resistance trim pot to adjust the digital display to the same temp reading as the thermistor is regulating the cabinet at. Best checked with a fridge thermometer of course. That might keep you going for a while until a full repair.
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