Isotherm watercooled pump not ticking on

[katandseiorse]

We have an Isotherm 4201 magnum ASU fridge and separate freezer systems, both watercooled.
It was a hot summer here in Australia and our water pump stopped running even though the Danfoss Compressor still ticked on and off as normal.

We did the trouble shooting with the jumper lead, and also put the power direct to the water pump and it ran ok. What could be the issue? We are hoping we don’t need a new black box as we have already replaced that about 4 years ago.

Our cabinet where the compressor unit etc is mounted may have got to around 40 degrees Celsius. Can hot weather cause the black box to overheat and stop working properly?

I’m writing this on behalf of my boyfriend who has done the technical hands on troubleshooting, sorry I’m using simplified terms.

Thanks in advance for any tips.

[OzePete]

Hi from another Ozzie!
If the pump ran ok when wired direct may I suggest the following:
Obtain a small 12VDC relay from Jaycar or similar.
Power the relay coil from the fan terminals on the MDM (Motor Driver Module. Black box terminals + and F ... usually third and forth from the top.) Send power from the 12VDC supply to the pump via this relay.

The MDM doesn't permit constant current greater than 0.5 amps and if your pump is powered from there then it will cut out and the above will prevent that.

Hot weather shouldn't effect the MDM black box as they have auto resetting high temperature cut out protection inbuilt.

Cheers OzePete

[Richard Kollmann]

Originally Posted by katandseiorse

We have an Isotherm 4201 magnum ASU fridge and separate freezer systems, both watercooled.
It was a hot summer here in Australia and our water pump stopped running even though the Danfoss Compressor still ticked on and off as normal.

We did the trouble shooting with the jumper lead, and also put the power direct to the water pump and it ran ok. What could be the issue? We are hoping we don’t need a new black box as we have already replaced that about 4 years ago.

Our cabinet where the compressor unit etc is mounted may have got to around 40 degrees Celsius. Can hot weather cause the black box to overheat and stop working properly?

I’m writing this on behalf of my boyfriend who has done the technical hands on troubleshooting, sorry I’m using simplified terms.

Thanks in advance for any tips.

That is a $270 us dollar variable speed water pump the electrical drawing in manual may help. Page 6 and 7.
https://www.indelwebastomarine.com/f...701-manual.pdf

[Richard Kollmann]

Originally Posted by Richard Kollmann

That is a $270 us dollar variable speed water pump the electrical drawing in manual may help. Page 6 and 7.
https://www.indelwebastomarine.com/f...701-manual.pdf

Operating unit without water pump is a bad practice and will damage electronic module attached to compressor and shorten life of compressor. After looking at the manual it is best you contact someone like John at: sales@coldeh.com
This is a Canadian company experienced with several of the Isotherm water cooled pump problems. Disconnecting and bypassing present pump controller may effect the ASU as well. Also bypassing pump controller will keep pump running at max speed.

[katandseiorse]

As soon as we noticed the water pump was not going when the compressor turned on we turned the fridge off. When the compressor was going there was only .18 volts coming from the electronic module to the water pump. Our pump is fine.

[Wavehiker]

Check intake thru Hull strainer. My pump stopped working and the cause was a clogged strainer.

[Richard Kollmann]

Originally Posted by katandseiorse

As soon as we noticed the water pump was not going when the compressor turned on we turned the fridge off. When the compressor was going there was only .18 volts coming from the electronic module to the water pump. Our pump is fine.

You may only get .18 volt if you measure Wires coming off Module terminals small plus brown wire and F blue wire terminals. These are control wires for electronics isotherm box.

The black and red wires to actually power pump source are attached before the compressor gets its power. See manual diagram.

If you are saying you get .18 amps on the two right hand terminals on the box marked Isotherm speed control and the power terminals at top of diagram have battery voltage then the pump controller must be faulty.

If you have no other solution Pete recommendation of removing wires from terminals small+ and F and connecting a small relay control there and picking up power at the terminal block before Danfoss module adding a safety fuse to wire the pump will operate when it is supposed to but at a higher faster sound level.

[Mike Banks]

If the refrigerator is running and the water pump is not, I would simply wire the pump to a separate switch altogether and put it next to the master switch for the refrigerator. Mark them refrigerator 1 and 2. One is the water pomp, you turn the on in order and off in reverse order. The only thing is, the water pump will run all of the time,. Not as big a deal as you would imagine--

That will get you going until you can make better repairs.

The other permanent way to do it, when you can buy parts, is to wire the water pump through a good quality platinum-contact relay activated through the motor switch. When the motor turns on, so does the water pump.

[Richard Kollmann]

[QUOTE=Mike Banks;2862679]If the refrigerator is running and the water pump is not, I would simply wire the pump to a separate switch altogether and put it next to the master switch for the refrigerator. Mark them refrigerator 1 and 2. One is the water pomp, you turn the on in order and off in reverse order. The only thing is, the water pump will run all of the time,. Not as big a deal as you would imagine--

That will get you going until you can make better repairs.

The other permanent way to do it, when you can buy parts, is to wire the water pump through a good quality platinum-contact relay activated through the motor switch. When the motor turns on, so does the water pump.[/QUOTE

Unfortunately this system if pump were operated by an independent switch each time compressor cycles off you would need to manually operate the pump. The thermostat can not be used because that current is only one to 5 ma. The circuit that controls the pump is limited to 1/2 amp. The temporary solution is the way Pete recommended in the above post