Fridge frustrations

[Graham]

Fridge frustrations; some hive mind assistance from the cogniscenti would be really welcomed please.

The fridge will not start; or if it does, only for moments few. A per many others, the relay fires but fridge doesn't hold on. Earth shunt is good (shunt repair in place), the relay (new) is good and the leisure batteries (new) good (and kept topped up via solar). Symptoms are the same whether on battery or hook-up.
Fridge removed and have proven that (with thanks to Penguin refrigeration fault guides) when directly connected to a good 12v battery and the thermostat bypassed with link wire, the compressor runs continuously and cools the box. So it doesn't appear to be an issue with the cold-making end of things.
The fridge thermistor provides a resistance reading (9.8kohm at about 18c, but no idea if this is in spec).
So now I think one of 2 faults possible: danfoss fridge controller; something on the van-side power or control system.
As I can get the fridge compressor to run, the fridge controller shows no fault code.
On the van side, I have proven a good 13.6v to the fridge supply. With the van control unit on, I can see a 4.8v control signal across the white/brown & green/brown (thermistor) pair - is this expected? This sinks to 0v when van control unit is off.
On the fridge side, I can see 68ohms between the brown (ground) and yellow so I don't think it is the control board resistor others have written about. But that still doesn't mean the fridge controller is fault free.
So I am a bit baffled. I'm leaning toward the fridge control unit but still not quite convinced.
What thoughts from the hive mind?
Thanks

 

[flying banana]

Thermistor vary their resistance dependant on temperature. Try testing it again but heat it up or cool it down and see if that resistance alters. If not then that's the issue

 

[WelshGas]

Fridge frustrations; some hive mind assistance from the cogniscenti would be really welcomed please.

The fridge will not start; or if it does, only for moments few. A per many others, the relay fires but fridge doesn't hold on. Earth shunt is good (shunt repair in place), the relay (new) is good and the leisure batteries (new) good (and kept topped up via solar). Symptoms are the same whether on battery or hook-up.
Fridge removed and have proven that (with thanks to Penguin refrigeration fault guides) when directly connected to a good 12v battery and the thermostat bypassed with link wire, the compressor runs continuously and cools the box. So it doesn't appear to be an issue with the cold-making end of things.
The fridge thermistor provides a resistance reading (9.8kohm at about 18c, but no idea if this is in spec).
So now I think one of 2 faults possible: danfoss fridge controller; something on the van-side power or control system.
As I can get the fridge compressor to run, the fridge controller shows no fault code.
On the van side, I have proven a good 13.6v to the fridge supply. With the van control unit on, I can see a 4.8v control signal across the white/brown & green/brown (thermistor) pair - is this expected? This sinks to 0v when van control unit is off.
On the fridge side, I can see 68ohms between the brown (ground) and yellow so I don't think it is the control board resistor others have written about. But that still doesn't mean the fridge controller is fault free.
So I am a bit baffled. I'm leaning toward the fridge control unit but still not quite convinced.
What thoughts from the hive mind?
Thanks

Did you clear any Diagnostic errors on the Control Panel?

 

[Graham]

Did you clear any Diagnostic errors on the Control Panel?

Hi, yup. Though at the moment they won’t clear as the fridge is out. But when it was in, yes. In fact when the fridge was in it showed no error codes but I reset the panel many times. Fridge out it shows errors 3101 and 3011 which are consistent with it being disconnected.

 

[Graham]

Thermistor vary their resistance dependant on temperature. Try testing it again but heat it up or cool it down and see if that resistance alters. If not then that's the issue

Thanks.

 

[Graham]

Did you clear any Diagnostic errors on the Control Panel?

Well, that was a turnup for the books...
Thanks to Penguin telephone advice, became confident that the issue wasn’t the fridge so put it back in. This time, because the control unit had already registered faults (fridge out) and I’d raised the roof to refit the fridge, the control panel remained on throughout. When I’d plugged the fridge back in, I then cleared the faults from the control panel and, hey presto, fridge sprang to life.
So it looks like the control unit had trapped a logic fault which wouldn’t clear until it acknowledged it had seen a ‘fault’.
Lesson.... unplugging the fridge forces the CU to acknowledge a fault which can then be cleared. Without actually unplugging the fridge, no end of CU resets On a ‘no fault’ condition are going to untrap the logic state.

 

[Graham]

Not so clever after all.....
went to turn the fridge on this morning: same bl**dy problem. Keeps tripping off. Leisure batteries full. Van interior cool. Tried the frig in my last post and it didn't work! Aaaargh!
Back to square one.
Because I categorically know the fridge actually works, I'm now thinking the best solution is to wire in an independent switch and thermostat control unit and completely bypass the VW control unit. There's something very odd indeed going on.
Any ideas from the hive mind welcomed. Thanks.

 

[Graham]

Not so clever after all.....
went to turn the fridge on this morning: same bl**dy problem. Keeps tripping off. Leisure batteries full. Van interior cool. Tried the frig in my last post and it didn't work! Aaaargh!
Back to square one.
Because I categorically know the fridge actually works, I'm now thinking the best solution is to wire in an independent switch and thermostat control unit and completely bypass the VW control unit. There's something very odd indeed going on.
Any ideas from the hive mind welcomed. Thanks.

Oh, and 'go to VW' isn't the answer where I live. The dealership is shocking; only understands builder's vans.

 

[dfps]

Hi Graham,
I too have a problem with my fridge and need to remove the controller to send it to Pengiunfrigo for testing. I can then establish if its the controller or the compressor/fan
Due to limited access through the cupboard access panel I don't think I can remove the controller with the main part of the fridge left in situ. think I may have to remove the fridge complete to access the controller. ?
This morning I started a new post asking for help and advice on how to remove the fridge.
I can see from your posts that you have already done a fridge removal.
Would you by any chance be willing to offer me advice on how to remove the fridge please. ?
I understand the basics of the removal but there are a few details I would like to clear up before attempting it.
My vehicle is a 2007 T5 Cali SE

Thanks