Isotherm/Webasto fridge

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mikefleetwood

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As part of my refurb/upgrade of Musketeer (Moody 29) I've fitted a GE80 fridge kit into the ice box.
Evaporator plate fits neatly into the icebox with the thermostat/controller neatly in the corner. The compressor is in the locker just aft of the galley, so all very neat. I powered it up yesterday - current draw is less than 2A, which seems a bit low, but the plate doesn't seem to cool. I didn't leave it on for very long, maybe half an hour, but it didn't seem to be doing anything. I suspect the fan is running (visibly, it obviously is), but the compressor isn't. Any suggestions? My suspicion is that the two gas connections are insufficiently tightened (although I thought they were) so the gas circuit isn't circulating. Does this sound likely?
Many thanks.
 
it might be possible to confirm the compressor is running by feeling for vibration. Unlikely the gas connections are causing the compressor to not run but may be the cause of poor actual refrigeration. Loss of vacuum and gas would cause that. 2amp draw is a bit of a problem too much for just fan too little for compressor and fan.
Others might correct this guess. ol'will
 
I will investigate further today, whilst she's still on a pontoon (moves to mooring tomorrow). I thought the compressor was running as I could hear a quiet whirring sound, but can't remember if I could feel vibration. I guess another thing to check is the voltage (could be my wiring is too thin).
 
Sorry, I started this thread weeks ago, then forgot about it!

I've had a few other things to sort out and the boat is now on a mooring. Anyway, I checked the fridge again this afternoon. The cooling fan runs but I can't feel any vibration from the compressor. There is no sign of the evaporator plate getting cooler, and the compressor and cooling coils don't warm up.

The unit is located in the cockpit locker on the opposite side of the boat to the battery compartment, but the wiring route is a little convoluted (as the engine and cockpit are in the way). I've wired it up with 2.5mm wire, but with hindsight maybe it needs something thicker? I've ordered some more 5mm cable (the same as I used for the toilet) - should arrive tomorrow.

Any thoughts as to if this might fix it? Anything else I should try/check?

Thanks
 
From Google:

Inspect the Thermostat:
  • If the compressor isn't running, the thermostat might be faulty.
  • Use a jumper wire to connect terminals "C" and "T" on the electronics box. If the compressor starts, the thermostat needs replacement.
  1. 4. Examine the Electronics:
    • If the compressor doesn't run after testing the thermostat, the electronics box might be faulty.

    • Replacement of the electronics module is relatively straightforward.
useful link here:

https://keoghs.au/keoghsmarine/isot...er following,it removes from the refrigerator.

Check the Thermostat is set correctly first!
 
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The whole kit is brand new. The thermostat has a "stop/off" position and and moving it to any other position starts the fan but not much else. Next time I'm there (probably Thursday) I'll check it's wired correctly, and try shorting the terminals you suggest.
 
mikefleetwood said:
Sorry, I started this thread weeks ago, then forgot about it!

I've had a few other things to sort out and the boat is now on a mooring. Anyway, I checked the fridge again this afternoon. The cooling fan runs but I can't feel any vibration from the compressor. There is no sign of the evaporator plate getting cooler, and the compressor and cooling coils don't warm up.

The unit is located in the cockpit locker on the opposite side of the boat to the battery compartment, but the wiring route is a little convoluted (as the engine and cockpit are in the way). I've wired it up with 2.5mm wire, but with hindsight maybe it needs something thicker? I've ordered some more 5mm cable (the same as I used for the toilet) - should arrive tomorrow.

Any thoughts as to if this might fix it? Anything else I should try/check?

Thanks
Click to expand...
Wiring is far to thin, 5mm might be OK, i would have used even thicker. The current draw on startup is significant and will cause too much voltage drop with thin cables, so the compressor will not start.
 
PaulRainbow said:
Wiring is far to thin, 5mm might be OK, i would have used even thicker. The current draw on startup is significant and will cause too much voltage drop with thin cables, so the compressor will not start.
Click to expand...
Thanks Paul - I've got some 10 Gauge (5.26mm2 according to Amazon) arriving today. I think, although I've not measured it, the cable length is 2.5-3m. Hopefully that will be enough. (I've got enough coming to replace the feed to the adjacent diesel heater - that I've not finished installing yet, as I suspect that could have the same problem).

I'd looked at the rated current for the wire I used - supposedly 29A - and didn't consider voltage drop!

Mike.
 
Ok, so pulled through new cables today, as above. No difference in behaviour. Measures 12.2V across the fridge terminals. Current draw seems to be only 0.2A. As far as I can tell the compressor is running (as well as the fan). Tried to bypass the thermostat, as suggested by Yoda - same results.
When the fridge starts, there is an initial shake from the compressor then continuous light vibration (as I'd expect). The fan starts up after 30 seconds as described in the manual.

To my mind, that only leaves the gas circuit. Is it possible that the joints in the cooling circuit aren't done up tight enough to break the internal seal? Or, how critical really is bend radius? The manual is insistent on minimum radius 150mm, but they were coiled tighter than that when delivered! The bend through the wall of the icebox is pretty tight, but there was no other way to get the tube through.

Any ideas?
 
I have the same unit.
It’s been faultless since 2020, does a cracking job and doesnt draw much power. You can’t not hear the compressor running, it’s quiet but you know when it’s running. No need to second guess yourself.
From your description it sounds like the compressor is running which would eliminate voltage drop and suggest a gas problem.

How tight have you gone in the cooling circuit coil? Are the easy clip connectors properly secure?

For anyone else searching for this - on power supply, they have a low voltage cut off and it is sensitive. Even when that triggers the compressor usually gives a solid clunk before it tries to start up.
I used 6mm from 12v planet.
 
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