Replaced Controls on my Ironman Icecube 12 volt fridge - $18.00

randy h

Member
BACKGROUND:
I have the 50L Ironman Icecube fridge/freezer. It has the Danfoss/Secop BD35F compressor with the 101N0500 primary controller.
Ironman fridges have a secondary controller mounted next to the 101N0500 with leads up to the user interface mounted on top of the fridge near the lid hinge.
The temp sensor is connected to the Ironman secondary controller and is routed into a tunnel running into the bottom edge of the insulation next to the evaporator surrounding the cabinet.

This is pretty much the standard configuration for any brand of mobile fridge aimed at our market. The secondary controllers and user interfaces will be customized to the manufacturer's choice.
The secondary controller handles the logic of monitoring the fridge temp and telling the primary controller when to turn on the compressor.

View of Compressor and Controllers
labeled controller view.jpg

PROBLEM:
After five years of great service my fridge would no longer function. It would power on for about 3 seconds then turn off. After reading forum posts here and elsewhere about other brand fridge troubleshooting, I determined the thermistor (temp sensor) was probably bad. I emailed Ironman support twice for info on what NTC Thermistor the fridge used, but they were absolutely no help and never responded. I called my local vendor where I purchased the fridge and asked for the same info. They were cordial and said they would get back with me but never did. I called back asking for followup, but again, they said they would get back with me but never did. So I ordered a Thermistor for a different brand fridge to at least help me troubleshoot. Testing with that, the fridge would turn on and cool, but the temp readings were way off. Setting the user interface to -22 F would get the fridge to turn on, but the on/off cycle was such a large spread it was still unusable. I figured I just needed to find an NTC Thermistor with the resistance required by the secondary controller. I ordered a few different ones via amazon but never found one that would give the Ironman secondary controller the input it was expecting.

FIX:
Since I could not find the information I needed to get an NTC Thermistor to match the Ironman secondary controller, I decided to eliminate the Ironman secondary controller and find a controller with a published NTC Thermistor. With the help of other forum posts here and elsewhere that referenced using third party controllers (albeit with with a different Primary Controller: 101N0220), I found an inexpensive unit on Amazon that came with its own matching Thermistor. Its a secondary controller and user interface built into one unit.

Bayite DC 12V Fahrenheit Digital Temperature Controller 10A 1 Relay with Sensor. Link to Amazon
bayite DC 12V Fahrenheit Digital Temperature Controller 10A 1 Relay with Senso.jpg

In studying the Ironman basic diagram on the bottom of the fridge, diagrams from Danfoss/Secop on their 101N500 Primary Controller, and some hand drawn diagrams from forum posters I was able to logic out how to wire in the third party secondary controller.
I am including pics of the Ironman diagram and the Danfoss/Secop diagram, and my final diagram in case they will help others who need to tweak things to their particular use case.

Ironman basic diagram
Diagram Sticker Underside of fridge labeled.jpg

Danfoss/Secop Diagram for 101N0500
(full PDF with explanations attached to this post) (hopefully: I have never attached a pdf file before)
Danfoss Wire Diagram.jpg
I am also attaching the full PDF of the Danfoss/Secop instruction sheet to this post. I hope that works.

As you might observe by looking at the Danfoss/Secop diagram for the 101N0500 Primary Controller, a lot of what the Ironman secondary controller was handling, the 101N0500 can handle all by itself.
Here is my diagram showing how to wire the third party secondary controller to the 101N0500 primary controller. Eliminating the Ironman secondary controller and its User interface.
BD35F With 100N0500 with 3rd Party.jpg

NOTES:
1. I completely removed the Ironman Secondary controller, rather than just re-wire around it. That space was pretty packed to begin with. It also made room for a possible blow outward fan to compliment the factory suck inward fan on the other side of compressor.

2. The 100N0500 controller produces a flash code to present error indications. The Ironman Secondary Controller would interpret those and display E1, E2, etc. Since I eliminated the Ironman Secondary Controller, I still wanted a way to observe any errors. This was accomplished by connecting a small LED between Primary Controller connections D and +. This was optional and is not required for fridge operation.

3. The interior cabinet lamp and its door switch was powered by the Ironman Secondary Controller. I still wanted lighting and that too was re-wired direct to the 100N0500 controller - Red wire to A and black to C (the top C, there are two).
This was optional and is not required for fridge operation.

4. The fridge compressor can run at multiple speeds. The Ironman Secondary Controller offered a button for Economy vs MAX. The 100N0500 recognizes this request by a resistor in the trigger on circuit from the Secondary Controller. Since my third party controller did not have a Eco/Max feature I wired in a switch that when turned on, would bypass the resistor signalling Eco mode and a 2000 RPM compressor speed. With a 692 ohm resistor in that circuit, the compressor runs at 3000 RPM (Max mode). I stole the resistor from Ironman Secondary Controller board and wired onto the switch like in the following pic.
This was optional and is not required for fridge operation in Economy mode all the time.
switch with resistor.jpg
5. The third party controller provides features not offered by the Ironman secondary controller:
a. Temp Reader Calibration
b. Delta Adjustment - how far above set temp before compressor is triggered.
c. High Temp Alarm (visual flashing, not audible)

6. Mounting the third party secondary controller, optional error code LED, and the optional Eco/Max switch: At first I was going to mount the third party secondary controller to the side of the fridge somewhere, but I feared I would knock it off when wrestling the fridge in and out of my tiny Geo Tracker back seat. So I decide to try and mount it in the place of the original user interface. From the factory there is a wire chase tunnel from above the 101N0500 controller up to the top of the fridge where the user interface was mounted. After removing the factory interface and pulling its wires out, I ran mine up the same chase. The factory interface is only about a half inch deep. My third party controller is about 4 inches deep. So I had to dremel out the hole it used, past the plastic bottom into the insulation a bit. I then dremeled out the faceplate it attached to, to make a hole for my controller, a hole for the error code LED and hole for the Eco/Max switch. it was a tight fit and I had to tweak things a lot before it all fit, but now it looks pretty darn close to factory. Well, not really but as close as I could make it.
Here is a pic
3rd party controller mounted small.jpg

I hope this helps somebody. My goal was to gather all in one place the info that I had to look for far and wide to make this repair/mod. I would be happy to answer any questions if anyone has any.

randyh
 

Attachments

Gav110

New member
BACKGROUND:
I have the 50L Ironman Icecube fridge/freezer. It has the Danfoss/Secop BD35F compressor with the 101N0500 primary controller.
Ironman fridges have a secondary controller mounted next to the 101N0500 with leads up to the user interface mounted on top of the fridge near the lid hinge.
The temp sensor is connected to the Ironman secondary controller and is routed into a tunnel running into the bottom edge of the insulation next to the evaporator surrounding the cabinet.

This is pretty much the standard configuration for any brand of mobile fridge aimed at our market. The secondary controllers and user interfaces will be customized to the manufacturer's choice.
The secondary controller handles the logic of monitoring the fridge temp and telling the primary controller when to turn on the compressor.

View of Compressor and Controllers
View attachment 495351

PROBLEM:
After five years of great service my fridge would no longer function. It would power on for about 3 seconds then turn off. After reading forum posts here and elsewhere about other brand fridge troubleshooting, I determined the thermistor (temp sensor) was probably bad. I emailed Ironman support twice for info on what NTC Thermistor the fridge used, but they were absolutely no help and never responded. I called my local vendor where I purchased the fridge and asked for the same info. They were cordial and said they would get back with me but never did. I called back asking for followup, but again, they said they would get back with me but never did. So I ordered a Thermistor for a different brand fridge to at least help me troubleshoot. Testing with that, the fridge would turn on and cool, but the temp readings were way off. Setting the user interface to -22 F would get the fridge to turn on, but the on/off cycle was such a large spread it was still unusable. I figured I just needed to find an NTC Thermistor with the resistance required by the secondary controller. I ordered a few different ones via amazon but never found one that would give the Ironman secondary controller the input it was expecting.

FIX:
Since I could not find the information I needed to get an NTC Thermistor to match the Ironman secondary controller, I decided to eliminate the Ironman secondary controller and find a controller with a published NTC Thermistor. With the help of other forum posts here and elsewhere that referenced using third party controllers (albeit with with a different Primary Controller: 101N0220), I found an inexpensive unit on Amazon that came with its own matching Thermistor. Its a secondary controller and user interface built into one unit.

Bayite DC 12V Fahrenheit Digital Temperature Controller 10A 1 Relay with Sensor. Link to Amazon
View attachment 495373

In studying the Ironman basic diagram on the bottom of the fridge, diagrams from Danfoss/Secop on their 101N500 Primary Controller, and some hand drawn diagrams from forum posters I was able to logic out how to wire in the third party secondary controller.
I am including pics of the Ironman diagram and the Danfoss/Secop diagram, and my final diagram in case they will help others who need to tweak things to their particular use case.

Ironman basic diagram
View attachment 495507

Danfoss/Secop Diagram for 101N0500
(full PDF with explanations attached to this post) (hopefully: I have never attached a pdf file before)
View attachment 495509
I am also attaching the full PDF of the Danfoss/Secop instruction sheet to this post. I hope that works.

As you might observe by looking at the Danfoss/Secop diagram for the 101N0500 Primary Controller, a lot of what the Ironman secondary controller was handling, the 101N0500 can handle all by itself.
Here is my diagram showing how to wire the third party secondary controller to the 101N0500 primary controller. Eliminating the Ironman secondary controller and its User interface.
View attachment 495524

NOTES:
1. I completely removed the Ironman Secondary controller, rather than just re-wire around it. That space was pretty packed to begin with. It also made room for a possible blow outward fan to compliment the factory suck inward fan on the other side of compressor.

2. The 100N0500 controller produces a flash code to present error indications. The Ironman Secondary Controller would interpret those and display E1, E2, etc. Since I eliminated the Ironman Secondary Controller, I still wanted a way to observe any errors. This was accomplished by connecting a small LED between Primary Controller connections D and +. This was optional and is not required for fridge operation.

3. The interior cabinet lamp and its door switch was powered by the Ironman Secondary Controller. I still wanted lighting and that too was re-wired direct to the 100N0500 controller - Red wire to A and black to C (the top C, there are two).
This was optional and is not required for fridge operation.

4. The fridge compressor can run at multiple speeds. The Ironman Secondary Controller offered a button for Economy vs MAX. The 100N0500 recognizes this request by a resistor in the trigger on circuit from the Secondary Controller. Since my third party controller did not have a Eco/Max feature I wired in a switch that when turned on, would bypass the resistor signalling Eco mode and a 2000 RPM compressor speed. With a 692 ohm resistor in that circuit, the compressor runs at 3000 RPM (Max mode). I stole the resistor from Ironman Secondary Controller board and wired onto the switch like in the following pic.
This was optional and is not required for fridge operation in Economy mode all the time.
View attachment 495536
5. The third party controller provides features not offered by the Ironman secondary controller:
a. Temp Reader Calibration
b. Delta Adjustment - how far above set temp before compressor is triggered.
c. High Temp Alarm (visual flashing, not audible)

6. Mounting the third party secondary controller, optional error code LED, and the optional Eco/Max switch: At first I was going to mount the third party secondary controller to the side of the fridge somewhere, but I feared I would knock it off when wrestling the fridge in and out of my tiny Geo Tracker back seat. So I decide to try and mount it in the place of the original user interface. From the factory there is a wire chase tunnel from above the 101N0500 controller up to the top of the fridge where the user interface was mounted. After removing the factory interface and pulling its wires out, I ran mine up the same chase. The factory interface is only about a half inch deep. My third party controller is about 4 inches deep. So I had to dremel out the hole it used, past the plastic bottom into the insulation a bit. I then dremeled out the faceplate it attached to, to make a hole for my controller, a hole for the error code LED and hole for the Eco/Max switch. it was a tight fit and I had to tweak things a lot before it all fit, but now it looks pretty darn close to factory. Well, not really but as close as I could make it.
Here is a pic
View attachment 495542

I hope this helps somebody. My goal was to gather all in one place the info that I had to look for far and wide to make this repair/mod. I would be happy to answer any questions if anyone has any.

randyh
Thanks randyh
I was having trouble with my controller reading 15 degrees out
As you found with Iron man they don’t give a **** about backup and spare parts
I just had to allow for the temperature differential until now
I had planned to fix in good time similar to what you had done and when I started googling circuit diagrams for the danfoss controller your write up came up
It has made it a lot simpler for me

Cheers
Gav
 

ramen.zwagerman

New member
Hi Team,

Want to put my 2 cents forward as this post helped me to some degree, and this may assist others.

Not an iron man fridge but a cheap fridge running a secop compressor.

Failed thermistor replaced with 10k NTC thermistor was reading too low/cold (-15c at 20c.)

After some trial and error found a 2K NTC thermistor is pretty much perfect.

This item can be ordered off EBay, and can be soldered onto pre existing factory thermistor without too much work. You could also buy a cheap eBay thermistor with connector and replace the 10k thermistor probe end with a 2K one. No polarity when soldering (nil positive/negative to worry about).

Hope this helps.

2k thermistor is $2.50-$3.50.



Sent from my SM-G965F using Tapatalk
 

randy h

Member
Funny, I guess Jan 2021 a few fridges malfunctioned.
You thankers above are sure welcome.
By the way, this repair/mod has been working great ever since. The fridge lives in my car and runs 24\7. (I plug in a battery charger when docked in my driveway)
 
Last edited:

alia176

Explorer
I'm a Controls Engineer who has been out of the game for over ten years so this thread tickled my noggin a little and I enjoyed it.
 

alia176

Explorer
Coming from a pro that is nice to read. grin
You did a fantastic job of not only performing the task but also picto-documented everything perfectly. Anyone can follow your instructions and that is not always easy to achieve. Major kudos to you sir. 👏
 

randy h

Member
You did a fantastic job of not only performing the task but also picto-documented everything perfectly. Anyone can follow your instructions and that is not always easy to achieve. Major kudos to you sir. 👏
Very kind, alia176. Thanks friend.
 
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