T5 SE Aux Heater New Problem

[356DNA]

Any thoughts on this new issue?
T5 SE - new batteries x2 12 months ago
When the aux heater is left on overnight it will (usually about 6h in) go to a very fast fan mode for 30s and then cut off completely with the heater light on the control panel switching off. Voltage at this point reads 12.4 / 80%. It can be briefly restarted but won’t run properly until the engine is started. Works ok on EHU.
Earth shunt has been fitted on the van. Anything else to check / investigate?
Thanks.

 

[AlanC]

What setting do you have it on overnight?
It could be overheating, hence the fast fan speed followed by switching off?
Don't think it is the leisure batteries as they are new.

Alan

 

[CaliCZ]

Any thoughts on this new issue?
T5 SE - new batteries x2 12 months ago
When the aux heater is left on overnight it will (usually about 6h in) go to a very fast fan mode for 30s and then cut off completely with the heater light on the control panel switching off. Voltage at this point reads 12.4 / 80%. It can be briefly restarted but won’t run properly until the engine is started. Works ok on EHU.
Earth shunt has been fitted on the van. Anything else to check / investigate?
Thanks.

Hello, my issue is completely the same, also T5 SE, 2011 vintage, both leisure batteries changed recently. My issue is still open, not resolved. My idea is to check the aux heater low voltage cut off value (numerical value) in VAG com diagnostic system. I think it’s too high adjusted (around 12,3 V). The trouble is , I don’t know what figure is the right one ?

 

[WelshGas]

Hello, my issue is completely the same, also T5 SE, 2011 vintage, both leisure batteries changed recently. My issue is still open, not resolved. My idea is to check the aux heater low voltage cut off value (numerical value) in VAG com diagnostic system. I think it’s too high adjusted (around 12,3 V). The trouble is , I don’t know what figure is the right one ?

I think you will be out of luck as , as far as I can gather, the low voltage cut off is part of the Diesel Parking Heater electronics or the Control Panel itself.
If the Control Panel voltage does not drop to 11.5v, the Parking Heater cut off voltage, then I would look at the wiring and earth points used by the Parking Heater for any corroded leads or connections as these might be responsible for high resistance connections leading to the Parking Heater " seeing" a suboptimal supply overcome by plugging into EHU which produces a higher voltage Leisure supply.

 

[ArunAlec]

Any thoughts on this new issue?
T5 SE - new batteries x2 12 months ago
When the aux heater is left on overnight it will (usually about 6h in) go to a very fast fan mode for 30s and then cut off completely with the heater light on the control panel switching off. Voltage at this point reads 12.4 / 80%. It can be briefly restarted but won’t run properly until the engine is started. Works ok on EHU.
Earth shunt has been fitted on the van. Anything else to check / investigate?
Thanks.

Is there plenty of fuel in the tank? I think it needs be over the 25% mark for the heater to run.

 

[CaliCZ]

I think you will be out of luck as , as far as I can gather, the low voltage cut off is part of the Diesel Parking Heater electronics or the Control Panel itself.
If the Control Panel voltage does not drop to 11.5v, the Parking Heater cut off voltage, then I would look at the wiring and earth points used by the Parking Heater for any corroded leads or connections as these might be responsible for high resistance connections leading to the Parking Heater " seeing" a suboptimal supply overcome by plugging into EHU which produces a higher voltage Leisure supply.

Just did a test with the engine battery disconnected and to my surprise, parking heater does not operate and control panel calls "heater is not available" (should be clear for me also earlier, when no amps increase was on CP indicated at heater starting). That experience leads me to to think the heater drains the engine battery ! Do not understand that, since the car is original from works assembled. I do think, it´s the main cause of heater operating time limit in my case. (according the info I´ve got, can run 12 hours, depends on battery condition, before it stops).

 

[WelshGas]

Just did a test with the engine battery disconnected and to my surprise, parking heater does not operate and control panel calls "heater is not available" (should be clear for me also earlier, when no amps increase was on CP indicated at heater starting). That experience leads me to to think the heater drains the engine battery ! Do not understand that, since the car is original from works assembled. I do think, it´s the main cause of heater operating time limit in my case. (according the info I´ve got, can run 12 hours, depends on battery condition, before it stops).

The Control Panel requires power from the Engine Battery as well as the Leisure Batteries to be fully functional.
Unless the vehicle has been rewired the Parking Heater only gets its power from the Leisure Batteries.

 

[CaliCZ]

The Control Panel requires power from the Engine Battery as well as the Leisure Batteries to be fully functional.
Unless the vehicle has been rewired the Parking Heater only gets its power from the Leisure Batteries.

if the heater gets its power from the Leisure batteries, then Amps increased value should be on Control Panel indicated, but I can see no electric current change, ...in case of fridge "on" I can see that (works also with Engine battery disconnected, control panel as well as), assumed should work both the same.

 

[WelshGas]

if the heater gets its power from the Leisure batteries, then Amps increased value should be on Control Panel indicated, but I can see no electric current change, ...in case of fridge "on" I can see that (works also with Engine battery disconnected, control panel as well as), assumed should work both the same.

That's how mine works. Upto -17amps on Parking Heater Start.

I have no time limit on Parking Heater function. On EHU unlimited, maximum I've done is about 6 days continuous. On Leisure Battery 3 days or so.

 

[CaliCZ]

Any thoughts on this new issue?
T5 SE - new batteries x2 12 months ago
When the aux heater is left on overnight it will (usually about 6h in) go to a very fast fan mode for 30s and then cut off completely with the heater light on the control panel switching off. Voltage at this point reads 12.4 / 80%. It can be briefly restarted but won’t run properly until the engine is started. Works ok on EHU.
Earth shunt has been fitted on the van. Anything else to check / investigate?
Thanks.

What I recommend is to check the heater connection to the right battery. My has been connected incorrectly to the engine battery from works !!!, (T5 SE 2011) Fixed up last week at aux heater specialized garrage. Before it was the same story at me, just left on overnight and then nothing. There is discharge protection on engine battery to prevent it, that´s why heater cannot run more.
Also please check if amps is indicated on control panel display while heater operates (there was nothing at me before).