Isotherm frig ICT removal and test results

[GeorgeRad]

But couldn't one control the speed by simulating that speed resistor thing? Or is that not there anymore?

Still is, didn’t change with newer SECOPs. These are ICT available functions, no clue which one required reprogramming, perhaps soft start.

 

[booster]

With ARV I have a three year bumper to bumper warranty of everything they did or put in. I am not going to carry spare parts on the come for the first three years. For instance I had a VB air suspension bag leak and they overnighted the parts to a MB Sprinter dealer where I was at in Texas and the dealer installed it and I was out before noon. In Phoenix they did the same with the Nations second alternator replacement and I got in and out again before noon. I don't know how they do it but they do it and promptly.

Can't blame you for that, but I do think it would be nice if you contacted ARV and asked about it so they can check it out and if there would be an issue they could decide to stock or not stock parts or come up with another way. If something happens and you have the same issue you would with an ITC, warranty won't matter, and if ARV doesn't know about the issue and way to get around it, your trip is still ruined.

 

[@Michael]

So, is there any particular reason one couldn't build a DIY fridge controller with an Arduino-class device and some temperature sensors? Does not look like rocket science.

If only to replace the function of the thermostat, I'd guess yes. If one were to try to replace the functionality of the electronic module, I suspect it would be difficult.

Here's a couple of threads where attempts are being made to repair the modules:

https://www.cruisersforum.com/forum...0f-101n0500-refrigerator-problems-218711.html

https://www.cruisersforum.com/forums/f115/3-flashes-on-danfoss-control-184322.html

 

[Davydd]

I carry a large Igloo cooler mostly for miscellaneous storage that can be used in an emergency if the refrigerator malfunctions. Refrigerator loss will not ruin my trips. It will be inconvenienced. I placed the refrigerator conveniently 18" off the floor to create an open notch used for many things like my custom ladder to the bunk bed, shoes, and sometimes a kitty litter tray when we bring our cat. It can serve to store a cooler in an emergency. It sits on a shelf in our vertical back storage of adjustable shelves and 27 cubic feet of storage.

 

[avanti]

If only to replace the function of the thermostat, I'd guess yes. If one were to try to replace the functionality of the electronic module, I suspect it would be difficult.

Here's a couple of threads where attempts are being made to repair the modules:

https://www.cruisersforum.com/forum...0f-101n0500-refrigerator-problems-218711.html

https://www.cruisersforum.com/forums/f115/3-flashes-on-danfoss-control-184322.html

I certainly wouldn't attempt to replace the SECOP controller. But, a homemade electronic thermostat/temperature controller looks pretty doable. Adding sensible "smarts" would be easy and fun. I may give this a try eventually, but my list of projects for our new rig is getting mighty long.

 

[avanti]

Looks like the Cruise 195 may be a good compromise, both size-wise and cost. Looks like a nice step up from the NovaKool.

We've looked carefully, and the choice is down to another NovaKool RFU6800 or the Isotherm Cruise 195. All the other obvious choices are either too wide for our space or have too small a freezer. Here are the tradeoffs:

NovaKool pros:
--less expensive
--known quantity
--a bit narrower
--slightly larger freezer

Isotherm pros:
--dual compressors
--slightly larger total capacity
--seemingly somewhat higher build quality
--adjustable shelves

Close call. Thoughts?

 

[GeorgeRad]

The Isotherm's picture shows electromechanical thermostat in the fridge compartment but not in the freezer so how is freezer temperature controlled. If there are 2 thermostats independent control could be great.

Nova Cool fridge with one thermostat, seems as mechanical thermostat. Bothe chambers have seperate evaporating plates, could have difficulties controlling both chambers temperatures correctly.

If you plan is to go with a large battery bank I would go with Isotherm.

I would check if Isotherm is not using electronic thermostat(s) like ICT or similar, their online onfo could outdated.

 

[avanti]

The Isotherm's picture shows electromechanical thermostat in the fridge compartment but not in the freezer so how is freezer temperature controlled. If there are 2 thermostats independent control could be great.

There are separate stats. Parts diagram found here:
Parts List Diagrams : Isotherm-Parts, Isotherm Marine Refrigeration and Parts

Nova Cool fridge with one thermostat, seems as mechanical thermostat. Bothe chambers have seperate evaporating plates, could have difficulties controlling both chambers temperatures correctly.

Yes, NovaKool has only one mechanical stat. We get by with it, but it is not great. Definitely no rock-hard ice cream.

I wonder what the power implication is for dual compressors. I could actually see it going either way, though likely some penalty. I am told that startup takes a lot of power, and there would be more of those, probably.

 

[GeorgeRad]

There are separate stats. Parts diagram found here:
Parts List Diagrams : Isotherm-Parts, Isotherm Marine Refrigeration and Parts


Yes, NovaKool has only one mechanical stat. We get by with it, but it is not great. Definitely no rock-hard ice cream.

I wonder what the power implication is for dual compressors. I could actually see it going either way, though likely some penalty. I am told that startup takes a lot of power, and there would be more of those, probably.

Perhaps it is time to think about soft start. Two compressors will work at lower duty cycles, finding efficiency energy vs power draw could help to make a decision. I think I have seen it somewhere in the vast Danfoss library.

 

[booster]

I would have to agree on the two compressor system, if it has to thermostats being a huge deciding factor. A single compressor and an adjustable cold air between frig and freezer works fine on home frigs, we have one currently, but when you get to highly variable conditions that a frig sees in a a camper a single has some balance between frig and freezer issues. We all see that.


My huge disqualifier would be if the Isotherm is using their electronic controls of any sort. They just don't do a good job with them, IMO. If it could be had with two mechanical thermostats, you would be able to put on either a manual speed and temp control system on each, or the home automation style you spoke of designing. By starting the compressors on the lowest speed, you can reduce the load and be easier on the compressor. Probably not as good as a soft start, but better than starting at higher speeds and loads. Two compressors probably would use a bit more power, but if you ran the freezer at the warmer temp that NovaKool does, you probably would be close.



Interesting choices to consider, good luck with it.

 

[avanti]

I would have to agree on the two compressor system, if it has [two] thermostats being a huge deciding factor.

If you plan is to go with a large battery bank I would go with Isotherm.

OK. One decision made.
I am holding the two of you personally responsible.

 

[GeorgeRad]

OK. One decision made.
I am holding the two of you personally responsible.

Make sure that whoever is going to convert your van follows Isotherm instruction.

You could consider floor vent hole, Dave Orton had them in both of his conversions and strongly recommends them. It could open only if needed. https://sprinter-source.com/forums/index.php?threads/38276/#post-879254.

Either backdraft or motorized valve could be used https://www.amazon.com/Fincos-Plastic-Electric-Motorized-Ventilation/dp/B07RQF86YS?th=1

For my small fridge I didn’t find it necessary but with large fridge it could help in hot days.

 

[avanti]

Make sure that whoever is going to convert your van follows Isotherm instruction.

You could consider floor vent hole, Dave Orton had them in both of his conversions and strongly recommends them. It could open only if needed.
...
For my small fridge I didn’t find it necessary but with large fridge it could help in hot days.

Nah. Not necessary. Internal venting is fine.

If you think about it, all that heat that is being pumped out of the fridge is coming from inside your van, so there is no net heating, beyond whatever electricity the unit consumes.

[Remember: This is not significantly bigger than our current fridge, so I have data.]

 

[GeorgeRad]

........................
If you think about it, all that heat that is being pumped out of the fridge is coming from inside your van, so there is no net heating, beyond whatever electricity the unit consumes.

Correct, didn't think this way.

 

[GeorgeRad]

Finishing up on the ICT removal and mechanical thermostat reinstall on our 3.0cf Cruise Elegance frig. I also added a power on/off switch to remove all power from the frig so it can be ventilated without the light staying on, and put on a compressor speed 6 position selector switch. Long haul and expensive to get rid of the ICT after the temp sensor failed after one trip. The ICT reprogrammed the compressor control module so it had to be replaced, of all things. Totally ridiculous to make a product that way as it prevents using a simple thermostat as backup or if you just don't like the ICT as it is a kind of not great performer also.

Here are the power switch by the side of the frig door, and speed control in the kitchen above the frig along with our digital wireless frig thermometer.

The speed control is a 6 position selector switch in the thermostat wiring to the compressor module. One no resistance jumper and 5 different resistor values to give 6 speeds from 2000rpm to 3500rpm. The mounting is a piece of PVC drain line pipe and two discs of PVC sheet. Bottom is bigger to give the flange and is cemented on with pipe cement, and the top is the access and is screwed on. Two bullet connectors on the wiring in the mount.

Based on our old frig of the same size and brand we knew that 2000rpm is good almost all the time and finding the right combo of things to get the desired frig and freezer temps along with slow speed, could save a lot power use. The old frig freezer door did not shut tightly and new one does fit tightly and a different shroud on the freezer box and different drip tray meant starting from scratch to get the right temps.

I quickly found out the thermostat was also different on the new frig, and could only get to 20*F as the highest freezer temp even after max ranging the calibration screw adjustment. That was good for us though as don't do ice cream or long term storage in it. Stock the freezer ran a 6*F so used a lot more energy because of the colder evaporator. Stock it also ran at a bit under 3000rpm so that is less efficient.

After some messing around with the drip tray position, I found that the frig got to 37/39*F with the tray in place, but pulled away from the back of the frig as far as possible. Freezer held at 19-21*F. Both very good for how we want it to run.

It appeared to me that the frig was hardly running much, but did run a 24hr test on it to see what the actual energy use was.

Test conditions were the above frig temps, ambient 67*F steady, inside the shop so no wind or sun. Most of the test was run on shore power float charge at 13.1v and some on battery at high 12v range. Voltage didn't matter as I was measuring cumulative watt hours on a Wattsup hardwired into the power wire at the frig. Watt hours were converted to amp hours at 12.4v which would normally be a worst case average for us as we have a lot of battery and moderate use, plus solar holding up the voltage for nearly half the time if decent sun.

The results were very surprising to me.

24 hour watt hour usage was 177.7 watt hours.

At 12.4v that is 14.33 amp hours and very low for any frig. It is about 1/2 of what the frig in stock form and what on the ICT in the same conditions, even with the ICT in economy mode. It is also about 20% lower than similar testing I did on our old frig.

Of course real world use will be substantially more as we commonly saw 30-50% more power use in real life than controlled optimized testing, but even at 50% higher it would be very low power use for any frig. It will be interesting to see how it does in real life. I did set up the wiring with Delphi connectors so the Watts up is very easy to put in and out, and it can be reset by cycling the on/off frig switch so easy to use.

I am very glad to see the ICT and it's 6* temp swings and high energy use gone for good. Should never have believed the literature claims.


I probably will run a shorter timed energy use with the drip tray pushed all the way in to it's normal place as that should give 40-41* in the frig, which is the normal spec point for Isotherm. I will also turn up the shop heat to 77* for the test as that is also there standard test point. The lower frig temp should save some energy, but the warmer ambient should cost some energy so it will be interesting to see how that balances out.

Back to the future, I had ITC for a few years know, worked fine until now. The OLED display is so dim that it is difficult to adjust a setpoint, can’t be done during the day.

Isotherm had replacement OLED display part for ICT, I verified its availability with Isotherm (Indel Webasto Marine in Florida) and ordered it from Panther RV a month ago, no part, no notification. I called Panther RV – no clue, called Isotherm and learned that this part is no longer available with questionable future deliveries. I also learned that ITC will be discontinued due to compatibility with new models.

So here are my options:

1. Get a full new ICT – not available in US.

2. Follow Booster going back to electromechanical thermostat – new fridge controller (300-350$) and new thermostat ($70) plus a couple days of labor. This could be questionable on a 13 years old fridge
Get a new fridge dimensionally same as my Isotherm Cruise 85 – ($900-$1800)
Lessons learned:

3. Never buy OLED display which have life expectancy of about 2000 hrs. in yellow color, blue is even shorter. My Blue Sea gauges are dying one by one.

4. Proven technology of electromechanical thermostats for fridges is still the best choice.
Stay away from the Isotherm electronics business kindergarten level development.

Questions:

1. I am looking for a Fridge in similar size as Isotherm Cruise 85, about – 24.7” H x 18.7” W x 19.6” D / 25 ⅛"H x 20 ⅜"W x 21-1/8"D

2. Is there a major difference between OFF Indel B CR 85 and Isotherm Cruise 85, from the dimensions it seems as the same manufacturing and both use Danfoss? Could be that Isotherm is focused on Marine side of the business and OFF Indel on RV. Both have different mounts, Isotherm uses left/right flanges with screws form the front and OFF Indel has hidden holes inside fridges to use screws on the left and right side.

 

[booster]

Back to the future, I had ITC for a few years know, worked fine until now. The OLED display is so dim that it is difficult to adjust a setpoint, can’t be done during the day.

Isotherm had replacement OLED display part for ICT, I verified its availability with Isotherm (Indel Webasto Marine in Florida) and ordered it from Panther RV a month ago, no part, no notification. I called Panther RV – no clue, called Isotherm and learned that this part is no longer available with questionable future deliveries. I also learned that ITC will be discontinued due to compatibility with new models.

So here are my options:

1. Get a full new ICT – not available in US.

2. Follow Booster going back to electromechanical thermostat – new fridge controller (300-350$) and new thermostat ($70) plus a couple days of labor. This could be questionable on a 13 years old fridge
Get a new fridge dimensionally same as my Isotherm Cruise 85 – ($900-$1800)
Lessons learned:

3. Never buy OLED display which have life expectancy of about 2000 hrs. in yellow color, blue is even shorter. My Blue Sea gauges are dying one by one.

4. Proven technology of electromechanical thermostats for fridges is still the best choice.
Stay away from the Isotherm electronics business kindergarten level development.

Questions:

1. I am looking for a Fridge in similar size as Isotherm Cruise 85, about – 24.7” H x 18.7” W x 19.6” D / 25 ⅛"H x 20 ⅜"W x 21-1/8"D

2. Is there a major difference between OFF Indel B CR 85 and Isotherm Cruise 85, from the dimensions it seems as the same manufacturing and both use Danfoss? Could be that Isotherm is focused on Marine side of the business and OFF Indel on RV. Both have different mounts, Isotherm uses left/right flanges with screws form the front and OFF Indel has hidden holes inside fridges to use screws on the left and right side.

Isotherm has several versions of the 85L frig, ours is some newer version with the center mounted handle which sucks because of bad leverage so have to use two hands. The Indel looks to be the old version handle Cruise 85 like we used to have. Vitrifigo is also an Isotherm and has different shelf layout. I think all use the same Danfoss module cooling unit in the upper right corner in the rear.

With the removal of the plastic shroud around the freezer and going to the mechanical thermostat ours is running well and very consistently. I do have a home made compressor speed control on it and am running at 2nd to the slowest most of the time.

 

[GallenH]

Dumb question: So one thing I dislike about the old absorption fridge is that the thermostat needs constant readjusting; a higher value in the day and lower in the night to keep up with changes in the ambient temp. With the fridges and controllers discussed above, do you just set 40º and the internal fridge temp remains there regardless of ambient conditions (like a home fridge)?

 

[GeorgeRad]

Isotherm has several versions of the 85L frig, ours is some newer version with the center mounted handle which sucks because of bad leverage so have to use two hands. The Indel looks to be the old version handle Cruise 85 like we used to have. Vitrifigo is also an Isotherm and has different shelf layout. I think all use the same Danfoss module cooling unit in the upper right corner in the rear.

With the removal of the plastic shroud around the freezer and going to the mechanical thermostat ours is running well and very consistently. I do have a home made compressor speed control on it and am running at 2nd to the slowest most of the time.

I checked Vitrigo, but it has a very different mounting system, OFF Indel is also very different. I am exchanging ma saga messages with folks from Indel B USA (2025 merger with Indel Webasto Marine) , and it is looking very positive.

Do you have a diagram of your speed control and soft start with the electromechanical thermostat?

I had a good share of problems with my fridge:

- Changing from capillary to Isotherm SEC, worked fine until
- SECOP 101N0500 failed, so new SECOP 101N0510
- Changing SEC to ICT, worked OK until OLED died
- Now – a new fridge or another fix

And now a dilemma what to do with 13years old fridge, fix it or replace it with a new one. I hope to minimize my time needed for a solution so replacing with identical mount fridge would require least of my time (4 front screws) but going back to a capillary a little more, so it will boil down to cost.

I will need to replace a galley panel (see the picture) on my galley or cover ICT holes. All four OLED displays I have (Blue Sea Voltage, Alternator charging current, ambient temperature and ICT are almost dead. I finely found a 4 digits voltage gauge with LED display DMR20-10-DCM

 

[GeorgeRad]

Dumb question: So one thing I dislike about the old absorption fridge is that the thermostat needs constant readjusting; a higher value in the day and lower in the night to keep up with changes in the ambient temp. With the fridges and controllers discussed above, do you just set 40º and the internal fridge temp remains there regardless of ambient conditions (like a home fridge)?

Yes, a temperature sensor is inside the fridge. For electronic thermostats the sensor is located in a refrigerator space and with a capillary bulb sensor near or at freezer's cold plate. Variation of ambient external temperature will impact compressor duty cycle and compressor RPM.

 

[GeorgeRad]

I found the diagram of speed contol, seems a simple inline with thermostat multiresistor switch, correct?