Danfoss BD2.5 12V Fan works on Freeze but not Normal thermostat setting

[eebygum]

Hi.
Any thoughts on why my fan only works in freeze mode ? Is my controller knackered ?

I have a Danfoss Bd2.5 Isotherm fridge which has an issue with 12V cooling fan (I’ve tested this connected directly to the battery and it works fine)

If my Isotherm controller is set to the freeze setting the 12V fan STARTS and runs, the compressor runs fine, the plate starts frosting

If the Isotherm is set to normal the 12V fan does NOT start, the compressor starts as normal.

Input voltages are all good when testing in both modes.

I can bypass the thermostat by jumping T&C and the compressor starts but the fan does not run.

I’ve ran an LED test between the C&D terminals when running in normal mode and it’s constantly on … suggesting a controller board issue ?

Any thoughts on how I can fix to work in Normal Mode. I was thinking I could just wire the fan directly to the +ve and -ve inputs to the controller and then it would always come on when the fridge is switched on… which is the outcome I want or am I missing something as to why that’s a bad idea !

 

[GHA]

You could try asking an AI, generally will return good answers with useful links, https://www.perplexity.ai/ is my AI of choice, seems to search latest web data as well, check out link 7 down the bottom...
Where google will return what you hope is the answer inside a web page, AI will give a condensed overview of the better links found, then you can keep asking more questions to get more refined results. Extremely useful, for writing a little tutorial of a program or searching for specific spare parts...
Doesn't cut n paste the links very well though.

have a Danfoss Bd2.5 Isotherm fridge which has an issue with 12V cooling fan (I’ve tested this connected directly to the battery and it works fine)If my Isotherm controller is set to the freeze setting the 12V fan STARTS and runs, the compressor runs fine, the plate starts frosting If the Isotherm is set to normal the 12V fan does NOT start, the compressor starts as normal. Input voltages are all good when testing in both modes.I can bypass the thermostat by jumping T&C and the compressor starts but the fan does not run.I’ve ran an LED test between the C&D terminals when running in normal mode and it’s constantly on … suggesting a controller board issue ?Any thoughts on how I can fix to work in Normal Mode. I was thinking I could just wire the fan directly to the +ve and -ve inputs to the controller and then it would always come on when the fridge is switched on… which is the outcome I want or am I missing something as to why that’s a bad idea !​

Sources
Troubleshooting Isotherm Refrigerator - Cruisers & Sailing Forums



cruisersforum
·
1
Isotherm Fridge fan failing - Trawler Forum



trawlerforum
·
2
Isotherm Cruise 130 Clean Touch any cooling issues? | Page 3



sprinter-source
·
3

Show all

Answer
It seems you're experiencing a common issue with your Danfoss BD2.5 Isotherm fridge, where the 12V fan operates only in freeze mode but not in normal mode. Here are some insights and potential solutions based on your description and similar cases:

Understanding the Problem​

1. Fan Operation: The fact that the fan works when connected directly to the battery and runs in freeze mode indicates that the fan itself is functional. However, it does not activate in normal mode, which suggests a control issue rather than a hardware failure of the fan.
2. Controller Behavior: The LED test between terminals C&D being constantly on during normal mode may indicate that the controller is not properly signaling the fan to turn on. This could be due to a malfunction in the control board or a fault in the thermostat settings.

Potential Solutions​

1. Bypass the Fan Control: As you mentioned, wiring the fan directly to the positive and negative terminals of the controller would ensure it runs whenever the fridge is powered on. This solution is effective but comes with considerations:
   • Continuous Operation: The fan will run continuously, which may lead to increased power consumption.
   • Temperature Regulation: Without automatic control, you might risk overcooling or affecting food storage conditions if the fan runs when unnecessary.
2. Inspect Thermostat Settings: Ensure that the thermostat is functioning correctly. Sometimes, recalibrating or replacing the thermostat can resolve issues where it fails to trigger auxiliary components like fans.
3. Check for Voltage Drops: While you've confirmed input voltages are good, intermittent voltage drops can still occur under load. Inspect connections for corrosion or loose wiring that might affect performance.
4. Control Board Replacement: If other troubleshooting steps fail, consider replacing the control board. In many cases, persistent issues with fan operation can be traced back to a faulty controller.
5. Community Insights: Similar cases discussed in forums suggest that many users have opted for hardwiring fans when faced with recurring control issues, often with satisfactory results as a temporary fix while awaiting more permanent solutions
   1
   2
   7
   .

Conclusion​

If you choose to wire the fan directly for immediate cooling needs, ensure you monitor its operation closely and consider addressing any underlying control issues later. This approach can provide a quick fix while allowing you time to explore more permanent solutions like replacing faulty components or recalibrating settings.

 

[eebygum]

WOW, that is extremely clever. I did quite a few searches before turning to YBW as a last resort but I definitely try the AI approach next time.

 

[GHA]

WOW, that is extremely clever. I did quite a few searches before turning to YBW as a last resort but I definitely try the AI approach next time.

Getting all the links from perplexity.io is really useful, AIs can & do make stuff up sometimes so worth a quick check in the links, though usually are very apologetic when you point it out
Also you can upload 5 documents of 12Mb like manuals & it will search through them, also very useful. Even without that finding some menu command you've forgotten the name of can usually be found quickly by describing what it does, lots faster than flicking through a fat manual or PDF!!