Demountable camper group

Got a Waeco CR110 that's being a real pain in the bum. Compressor and fan are running continuously. Fridge and freezer compartment are getting cold (very cold) but the compressor is not cycling on and off to maintain temperature, just running all the time, and is not responding to adjustments of the thermostat control. Obvious answer would be that the thermostat has gone - and that's what Waeco's trouble-shooting guide suggests - so I installed a new thermostat. No change! I'm stumped. Any suggestions? Does it sound like a problem with the compressor's electronic control unit? Done an email to Waeco but, as yet, no reply and their technical/customer support does not have a good rep. Help!!

If the thermostat is not the problem, i suspect the thermocouple sensor which provides the temperature information back to the controller. Can you open up the electronics to get a photo of the connections. This would help with diagnosis.

(From FB post)




heberger image

Check the wiring to the control unit is correct. Of course it could be a faulty control unit - they are pretty easy to change once you have the fridge out. The controller unit is Danfos - it comes with the compressor rather than being added by Waeco / Dometic. Waeco have technical support available.

The wiring diagram for the BD50, which should be similar to the BD35, shows the thermostat as being connected between pins T and C on the controller unit, and also conneted to pin P of the battery protection circuit.

Cheers,

Steve.

keeflester wrote:If the thermostat is not the problem, i suspect the thermocouple sensor which provides the temperature information back to the controller. Can you open up the electronics to get a photo of the connections. This would help with diagnosis.

I don't think the CR110 has a thermocouple. I think it just runs straight off a basic thermostat on the right hand side when you open the door. All the electrics external to the controller and compressor are connected to spade connectors on one end of the controller unit. So there shouldn't be any need to open up the controller unit. If you do it is all flow-soldered surface mount components, so not something to fiddle with, especially since Waeco will send you out a warranty replacement if needed.

By the way, if removing the controller unit, it may appear that all the connections are on the outboard end, but you will ask yourself how it is connected to the compressor - it will seem pretty stuck on there. Strangely the compressor has three pins in a triangular arrangement that stick out from its side and the controller is pushed sideways onto those pins - i.e. they penetrate three holes in the flat face of the controller - so when removing it you need to ease it away from the compressor.

Steve.

keeflester wrote:If the thermostat is not the problem, i suspect the thermocouple sensor which provides the temperature information back to the controller. Can you open up the electronics to get a photo of the connections. This would help with diagnosis.

I presume the thermocouple sensor is this wire that comes as part of the thermostat assembly, isn't it Keith?





It is just pushed in behind the plastic lining of the fridge wall. If it's that that is the problem then it means another complete thermostat I think.

sabconsulting wrote:

keeflester wrote:If the thermostat is not the problem, i suspect the thermocouple sensor which provides the temperature information back to the controller. Can you open up the electronics to get a photo of the connections. This would help with diagnosis.

I don't think the CR110 has a thermocouple. I think it just runs straight off a basic thermostat on the right hand side when you open the door. All the electrics external to the controller and compressor are connected to spade connectors on one end of the controller unit. So there shouldn't be any need to open up the controller unit. If you do it is all flow-soldered surface mount components, so not something to fiddle with, especially since Waeco will send you out a warranty replacement if needed.

By the way, if removing the controller unit, it may appear that all the connections are on the outboard end, but you will ask yourself how it is connected to the compressor - it will seem pretty stuck on there. Strangely the compressor has three pins in a triangular arrangement that stick out from its side and the controller is pushed sideways onto those pins - i.e. they penetrate three holes in the flat face of the controller - so when removing it you need to ease it away from the compressor.

Steve.

Thanks Steve, yeah you're right about the thermostat. I think it can only be the controller that's the problem. Sadly it's way beyond the terms of Waeco's warranty but that's very useful info about it's removal. Thanks a lot.

saDgit wrote:

keeflester wrote:If the thermostat is not the problem, i suspect the thermocouple sensor which provides the temperature information back to the controller. Can you open up the electronics to get a photo of the connections. This would help with diagnosis.

I presume the thermocouple sensor is this wire that comes as part of the thermostat assembly, isn't it Keith?





It is just pushed in behind the plastic lining of the fridge wall. If it's that that is the problem then it means another complete thermostat I think.

Yes Martin, but events have moved on. You have better help available here than I can offer.

I don't think that wire is a thermocouple, just a conductor to conduct the cold from the back of the fridge to the thermostat.

Thanks Keith for posting the photos. I admit I was lazy and just put them on fb rather than attempting to host them somewhere and put a link here.

I would check the wiring from the thermostat to the controller as it doesn't look like it was included with your replacement thermostat. I.e. if it is just a badly crimped connector then that would be a lot cheaper to fix than a replacement controller.

Steve.

sabconsulting wrote:I would check the wiring from the thermostat to the controller as it doesn't look like it was included with your replacement thermostat. I.e. if it is just a badly crimped connector then that would be a lot cheaper to fix than a replacement controller.

Steve.

Will do, thanks.

Any nearer Martin? I understand these compressor's are the best these days but own up to not understanding them properly