Isotherm problem

[Kestrahl]

Have a isotherm compact classic. The problem is it will turn on and run the compressor for 2 or 3 seconds then cut out. Replaced the electrics box, nothing changed. Shorted out the thermostat, still no change.. checked the voltage at the control box when the fridge turned on and seems fine, even ran new wires directly from the bus bars. Any ideas?

[OzePete]

Try disconnecting the fan. If the unit then runs, replace the fan.
Next, remove the Motor Driver Module (electrics box) and check the resistance between each two pins... should be all the same at approx 2 ohms. Also check from these pins to the compressor case to see if there is any continuity. (Motor winding shorting to frame)
What is the history of the system because the compressor itself is usually bullet proof and you have changed the driver, so the only thing left is an induced seized compressor!

Cheers OzePete

[Kestrahl]

Thanks for that. Turns out one of the fans had died. As soon as that was disconnected it works fine.

I added an extra fan here in the tropics to try and improve efficiency, if it only had one fan then I would have noticed that there was no fan sound!

[OzePete]

Originally Posted by Kestrahl

Thanks for that. Turns out one of the fans had died. As soon as that was disconnected it works fine.

I added an extra fan here in the tropics to try and improve efficiency, if it only had one fan then I would have noticed that there was no fan sound!

That is good news.
These little fans have a tiny built in processor which, if it fails, can corrupt the processor that drives the compressors Motor Driver Module on rare occasions.

I would be more concerned at your running two fans as this may exceed the Motor Drivers fan circuit limit.
We use a relay powered by the Motor Drivers fan circuit and supplying the fan (fans) direct from the 12VDC supply. This eliminates any chance of a faulty fan corrupting the Driver or overloading it.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems