Isotherm Fridge units

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sailor211

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We have a isotherm fridge unit with cooling plate. This has been working well and run for days on end over the past week or so more work than it has done in a couple of years with COVID etc.
It stopped a couple of days ago. The Cooling plate was frozen but did not remain cold. The indicator LEDs worked as normal switching from manual to auto.

When I got to the compressor there was a detectable quiet hum, when the compressor should run. A waggle of the orange control unit cause the leds to go out and the hum to stop. Total failure.
The control unit looks as good as new with no corrosion or overheating.

Is the cause likley to be the control unit ? I would have thought that the compressor should work forever is this correct?.

Before I splash out £325 on a new control unit, has anyone any knowledge or experiance with these units. Any testing tips ? before I start replacing the compaonents one at a time.?

Any suggestions mose welcome.

Thanks in advance


Mike
 
As much to keep your thread active as my being useful :)

I'd check the wiring, a jiggle of the unit should not stop a hum, indicating the unit might be working. The fact your coolling plate is frozen suggests, to me in my ignorance - suggests : it was cold, there was a lot of humidity (why else is it frozen) - and maybe the door was left open or the door seal is not good - and the fridge has been working its back side off.

I don't know your unit (mainly because I'm not a fridge expert and you don't give a model reference) but most of these units have a little computer fan that runs when the compressor runs. I'd also check the fuse, the fridge must be fused?

I'd then hope a fridge expert pipes up, and there are one or two here, with better and more useful information before your thread falls of the first page.

Good luck

Jonathan
 
a few pics wouldn;t go amiss. what controller, checked with a voltometer what the two top connectors show?
wiggling and stopping would have more to do with wires/crimping failing than anything else.
fan on the compressor spins? if fan is dying (happened to me) resistance increases, consumption goes over the .5A limit and compressor stops working. Unplugging the fan will fire up the fridge again.
quite a few tests/things to do before resorting to replacing bits, but to get any useful recommendations, we need more info
 
vas said:
a few pics wouldn;t go amiss. what controller, checked with a voltometer what the two top connectors show?
wiggling and stopping would have more to do with wires/crimping failing than anything else.
fan on the compressor spins? if fan is dying (happened to me) resistance increases, consumption goes over the .5A limit and compressor stops working. Unplugging the fan will fire up the fridge again.
quite a few tests/things to do before resorting to replacing bits, but to get any useful recommendations, we need more info
Click to expand...
I have 13V at the feed on the upper two cables.
do you know what there should be at the motor connections?

the controller is described as Red ASU Control Box by isotherm
 
sailor211 said:
I have 13V at the feed on the upper two cables.
do you know what there should be at the motor connections?

the controller is described as Red ASU Control Box by isotherm
Click to expand...
Sorry, I'll pass, never seen this controller before, I was assuming a danfoss bd35 compressor with its controller.
Otoh, 13v is good so you can most likely discard the low voltage as a problem.
 
I mislead you the unit was cold and frozen,
Neeves said:
As much to keep your thread active as my being useful :)

I'd check the wiring, a jiggle of the unit should not stop a hum, indicating the unit might be working. The fact your coolling plate is frozen suggests, to me in my ignorance - suggests : it was cold, there was a lot of humidity (why else is it frozen) - and maybe the door was left open or the door seal is not good - and the fridge has been working its back side off.

I don't know your unit (mainly because I'm not a fridge expert and you don't give a model reference) but most of these units have a little computer fan that runs when the compressor runs. I'd also check the fuse, the fridge must be fused?

I'd then hope a fridge expert pipes up, and there are one or two here, with better and more useful information before your thread falls of the first page.

Good luck

Jonathan
Click to expand...
I mislead you. The unit was frozen but over a day it thawed, all ice now gone. it is ambiant temp. crimps look good and fuse has been replaced incase there was high resistance there.

model is Isotherm 3201 ASU
 
You should be able to test the compressor by taking off the ASU unit, reconnect the power supply to the danfoss controller you will find underneath and rigging a jumper wire for the thermostat connections. Check on internet - should be loads of notes/videos on how to do this.

If the compressor starts up and stays running in this mode, the fault is is with the "eye waterly expensive Isotherm ASU unit.

Temporary fix is to buy and fit another thermostat to the Danfoss controller and run it without the ASU. I have been doing this for 6 years. The compressor will only run at low RPM but for £10, I bought a little piece of kit that plugs into the Danfoss compressor that allows me to manually increase the RPM (and the current drawn) of the compressor, useful after a defrost when I have shore power or lots of sun

.Another fault can be the Danfoss controller, they have been known to fail.

Below are my notes from the last time I had to fiddle with things, hope they make sense.


DANFOSS Controller connections
- BIG BLACK to BIG YELLOW to Battery –ve
+ BIG RED to BIG RED to 10 Amp Fuse to ON/OFF Toggle Switch to Battery +ve
+ BROWN + to Voltage reducer
F BLUE - to Voltage reducer
D Not used
C to Thermistor
P Not used
T to Thermistor

NOTES
1 & 2 - & + above are in large Letters

Replacement DANFOSS Thermistor pipe
Needs to be at least 230mm 7ft 6 inches long to fit my boat

NOTE
NEW ISOTHERM VOLTAGE REDUCERS ARE WIRED DIFFERENTLY TO THE OLD ONES, BELOW REFERS TO THE NEW TYPE
Voltage reducer to Danfoss (I had a Blue ASU and water cooling)
RED + To Battery Positive
BLACK - To Battery Negative
BROWN + To Small + 3rd Connector down
BLUE - To F 4th Connector down

ISOTHERM BLUE ASU Controller Connections
- BIG BLACK to BIG YELLOW to Battery –ve
+ BIG RED to BIG RED to Fuse to Toggle Switch to Battery +ve
BROWN + To Fan/Pump + 3rd Connector down
BLUE - To Fan/Pump - 4th Connector down

Voltage reducer to Isotherm ASU
RED + To Battery Positive
BLACK - To Battery Negative
BROWN + To ASA Fan/water pump + 3rd Connector down
BLUE - To ASU Fan water pump - 4th Connector down


Danfoss
Quick test
Fit 12V supply to new Thermistor from Danfoss controller
Power On compressor

Fit to pipe going into plate as close as you can to the plate,
Put Thermistor piping in plastic to protect it until it exits the fridge area
Route over the top of the plate if you can (I have a Eutectic plate)
Fit 12V supply to Thermistor from Danfoss controller
Power On compressor area & check compressor comes on
Check compressor turns off/on on Temp Control after getting down to temp

Have fun and good luck
 
A really good clean of both the male and female spade connectors would be a good idea.

Although you can sense 13v, this may not stay under load due to resistance on the connections.
 
john_q said:
You should be able to test the compressor by taking off the ASU unit, reconnect the power supply to the danfoss controller you will find underneath and rigging a jumper wire for the thermostat connections. Check on internet - should be loads of notes/videos on how to do this.

If the compressor starts up and stays running in this mode, the fault is is with the "eye waterly expensive Isotherm ASU unit.

Temporary fix is to buy and fit another thermostat to the Danfoss controller and run it without the ASU. I have been doing this for 6 years. The compressor will only run at low RPM but for £10, I bought a little piece of kit that plugs into the Danfoss compressor that allows me to manually increase the RPM (and the current drawn) of the compressor, useful after a defrost when I have shore power or lots of sun

.Another fault can be the Danfoss controller, they have been known to fail.

Below are my notes from the last time I had to fiddle with things, hope they make sense.


DANFOSS Controller connections
- BIG BLACK to BIG YELLOW to Battery –ve
+ BIG RED to BIG RED to 10 Amp Fuse to ON/OFF Toggle Switch to Battery +ve
+ BROWN + to Voltage reducer
F BLUE - to Voltage reducer
D Not used
C to Thermistor
P Not used
T to Thermistor

NOTES
1 & 2 - & + above are in large Letters

Replacement DANFOSS Thermistor pipe
Needs to be at least 230mm 7ft 6 inches long to fit my boat

NOTE
NEW ISOTHERM VOLTAGE REDUCERS ARE WIRED DIFFERENTLY TO THE OLD ONES, BELOW REFERS TO THE NEW TYPE
Voltage reducer to Danfoss (I had a Blue ASU and water cooling)
RED + To Battery Positive
BLACK - To Battery Negative
BROWN + To Small + 3rd Connector down
BLUE - To F 4th Connector down

ISOTHERM BLUE ASU Controller Connections
- BIG BLACK to BIG YELLOW to Battery –ve
+ BIG RED to BIG RED to Fuse to Toggle Switch to Battery +ve
BROWN + To Fan/Pump + 3rd Connector down
BLUE - To Fan/Pump - 4th Connector down

Voltage reducer to Isotherm ASU
RED + To Battery Positive
BLACK - To Battery Negative
BROWN + To ASA Fan/water pump + 3rd Connector down
BLUE - To ASU Fan water pump - 4th Connector down


Danfoss
Quick test
Fit 12V supply to new Thermistor from Danfoss controller
Power On compressor

Fit to pipe going into plate as close as you can to the plate,
Put Thermistor piping in plastic to protect it until it exits the fridge area
Route over the top of the plate if you can (I have a Eutectic plate)
Fit 12V supply to Thermistor from Danfoss controller
Power On compressor area & check compressor comes on
Check compressor turns off/on on Temp Control after getting down to temp

Have fun and good luck
Click to expand...
Hi John. Clearly you know what you are talking about. Your post where you refer to the eye watering price of the Isotherm ASU unit is exactly where I find myself and I was hoping to get in touch and ask you how you managed to get your system to work without replacing these parts. I have jumpered the C and T connectors on my controller and the compressor runs so clearly my controller is good. I however have no LEDs on the little control panel leading me to believe that the Red ASU unit attached to the controller is bad. Or the little ASU control pane. Any insight as to how you wrangled things to allow your system to run would be appreciated.
 
Metalicmike said:
Why does a simple thing have to be so complicated, what happened to the simple thermostatic switch :rolleyes:
Click to expand...
The compressor normally is fitted with one to detect the compressor temp/overheat....
Connections, lack of refrigerant, temp control stat, are simple causes of failure
 
billskip said:
The compressor normally is fitted with one to detect the compressor temp/overheat....
Connections, lack of refrigerant, temp control stat, are simple causes of failure
Click to expand...
Do the sensors actually make it better or just more to go wrong. How do the costs stack up if your your not a refrigeration engineer.
 
Metalicmike said:
Do the sensors actually make it better or just more to go wrong. How do the costs stack up if your your not a refrigeration engineer.
Click to expand...
The sensors protect from overload/fault damage ...if a person is able to diy repair the saving is on labour and parts mark up.

Sensors are not normally expensive...the knowledge and fridge guy's hourly rate and call out charge is what hits your wallet, and of course the risk of honesty....

I've known on many occasions expensive components are said to be faulty when in fact it's just minor things.
 
billskip said:
Sensors are not normally expensive...the knowledge and fridge guy's hourly rate and call out charge is what hits your wallet, and of course the risk of honesty....
Click to expand...

For many years, refrigerators and freezers for RV, boat and other recreational use have evolved very little and there has been a strange consensus among manufacturers about how high the price point should be. Compared to household appliances, they have been inexplicably expensive.

Italian Indel B is behind many devices in this category, sold under names such as Webasto (joint venture), Isotherm, Cruise and others.
Swedish Dometics is behind brands like Waeco and Mobicool.

There aren't many alternatives, especially if you need to replace and find new ones with the same dimensions. In the subcategory "coolers" there are some alternatives (e.g. HeroCamper, fridge/freeze box designed in Denmark).

The only cheaper alternative I've seen is German Belluna.eu. I bought an 85 litre fridge from them a year ago, with a removable freezer box (more space for refrigeration). I also had options to choose the door type (chose stainless steel) and which side to hinge it on. €525 + shipping €49.

More efficient, faster and less noise. I'm happier than with the Isotherm it replaced.
 
Last edited:
90% or my system is working correctly. I have confirmed that Refrigeration wise the system is good. I replaced the Danfoss controller, a 101N0220, and the system worked for a while. Probably was not required as the problem I had was intermittent problem and the LEDS on the ASU control panel would flicker and sometimes just not work. My guess is the Red ASU Control Box by isotherm was failing and the little walk around the boat gave it a new lease on life for a few days. Now I have no LED's at all. As good as dead. So due to the ridiculous price of the electronic Thermostat I want to replace the items below with a mechanical thermostat. This is what I am trying to find. My refrigeration system is an Isotherm 320I ADU from Indel Webasco Marine.
I am unable to find any info on this mechanical Thermostat however hopefully somebody had made this "upgrade"
Mechanical Thermostat.jpgElectronic ASU Theromostat.jpg
 
andyrauc said:
90% or my system is working correctly. I have confirmed that Refrigeration wise the system is good. I replaced the Danfoss controller, a 101N0220, and the system worked for a while. Probably was not required as the problem I had was intermittent problem and the LEDS on the ASU control panel would flicker and sometimes just not work. My guess is the Red ASU Control Box by isotherm was failing and the little walk around the boat gave it a new lease on life for a few days. Now I have no LED's at all. As good as dead. So due to the ridiculous price of the electronic Thermostat I want to replace the items below with a mechanical thermostat. This is what I am trying to find. My refrigeration system is an Isotherm 320I ADU from Indel Webasco Marine.
I am unable to find any info on this mechanical Thermostat however hopefully somebody had made this "upgrade"
View attachment 181243View attachment 181242
Click to expand...
Maybe you should try looking in air-conditioning suppliers or even the car a/c system...many of this type of mechanical stat were fitted old cars..

Sometimes it's necessary to be open mind about how you want to fix/repair things.

I found it was amazing how the workaround get it going abilities of the "third world" people in places like Africa and Venezuela get things working....
Ok, one has to close their concerns about efficiency and passing quality control etc...

Google "mechanical fridge thermostat " loads on there to choose from, and adjustable....
 
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