Anyone got experience with an Isotherm ITC control?

[booster]

I have been testing our new frig with it now fully mounted in the Roadtrek and the ITC is giving very large temp differential between the off and on cycles.



Every cycle, whether on automatic or ECO varies from 33 to 39*F, so a 6* differential. ITC temps shown match our old wireless thermometer so that part is good after setting a correction.


I have been corresponding with Isotherm USA and they do not know what the spec is and it doesn't seem to be published anywhere I could find. The differential is also not settable, which is odd for a digital thermostat, I think.


I put the unit back on the built in mechanical thermostat and the differential is less than 2*F so the box, compressor and install appear to be not an issue.


Anybody got any history or data on the ITC?

[rowiebowie]

I had to go to youtube to make sure what ITC was:

https://www.youtube.com/watch?v=N1JOtpTUJaM

It does seem odd that with all the features, being able to set a tighter temp differential is not one of them. But if you do nothing, 33-39 degrees will keep your food fresh.

[GeorgeRa]

If I understand it correctly the capillary probe is on the cold plate and electronic thermostat sensor within the fridge space. The response time could be much shorter than ITC one. The lag time of evaporator temperature change and compressor on/off should be very low.

[booster]

Originally Posted by GeorgeRa

If I understand it correctly the capillary probe is on the cold plate and electronic thermostat sensor within the fridge space. The response time could be much shorter than ITC one. The lag time of evaporator temperature change and compressor on/off should be very low.

Yep, that is how it is set up, so I would expect the frig based, electronic one to react faster to frig temp changes and counter them, but maybe not. Trying to keep the box at a constant temp based on keeping the freezer/evaporator at a colder temp would seem to be more difficult.


I have been rereading the instructions and descriptions of how the ITC is supposed to work, including what they call overcooling which is supposed to work like a cold plate but use the frig contents as thermal mass instead of a metal mass in the frig. Overcooling will cool to 5.4*F colder than setpoint with a low limit of 33* and is a manual turn on feature. It should only function when on charge level voltages and go off if not at those levels or in ECO mode when the compressor should run at the lowest speed all the time.


Since I get a consistent 33* on the low end all the time it may be the unit is stuck in overcooling all the time. I am going to hook it back up and do a full default reset and reenter everything and see what happens. I will also set the voltage settings as high as they will go so when the voltage starts to drop at all it should go out of overcooling which is turned off anyway and shouldn't be running. Maybe it will come out of it's weirdness, otherwise it probably needs a new circuit board.


I did find some posts on one of the sailor's forums of a couple of people who have the ITC units and several had problems and nobody seemed to be able to get them to work as they understood the directions to state, so not encouraging. Isotherm refused one of them a new circuit board to try to fix one of them and told them that overrcooling has to be shut off manually every time you turn off the motor, even though the instructions say otherwise. Also not encouraging.

[GeorgeRa]

My Smart Energy Controller is turn on with potentiometer on max low temperature set point. On other settings works just like a regular thermostat.
Perhaps SEC manual would be helpful if there is similarity between both units.

[booster]

Originally Posted by GeorgeRa

My Smart Energy Controller is turn on with potentiometer on max low temperature set point. On other settings works just like a regular thermostat.
Perhaps SEC manual would be helpful if there is similarity between both units.

That is one of their previous versions and they work differently. The do overcool, I think, but not the same way. Way different settings and controls. The ITC is supposed to go in and out of supercooling based on battery protection voltages, I think. And it should never supercool in ECO mode.

It appears that ours was stuck in supercooling mode like one of the posts I saw. He got his unstuck be unplugging it from all power for a while and then restarting it. He then toggled the supercooling setting on and off again and it began working more like the instructions say it will. I tried that this morning and it did stop going into supercooling I think, at least when on batteries, but haven't checked it on charge voltage. The auto compressor speed also seems to be working now instead of full speed all the time. Differential looks to be smaller but still pretty high, but need to wait until has run and stabilized a while[