Climatronic REST mode

[djjarvis]

Hi

Does anyone have a B8 with the REST function (residual heat) that actually blows warm air? Every time I've tried it, stopping for a break with a nice hot engine, it's only ever blown cold air at me!

Mine's the 1.4TSI 150PS and if I look on parts web sites they are willing to sell me an auxiliary water pump for this car. From that I deduce that it does have such a pump - I believe it may be located on the back-right corner of the engine head where the coolant lines go across to the firewall and back.

Dealer looked at the car, found no faults but acknowledged the REST mode goes cold after a few seconds. They concluded that on this car the REST mode only uses residual heat in the heater matrix. They referred me to the manual but in there it says that residual heat from the engine is used - a subtle but clear difference.

Are they correct and this feature is deliberately useless? I bet it would work properly on a diesel where I read that the auxiliary pump can also be used for cooling down an engine if it is stopped during a DPF re-gen.

[M1tchy]

My wife has it on her Touareg and I’ve got a similar feature on my A7. Neither have any additional heaters or auxiliary warming devices and both are fairly useless. They use the warm engine (not sure if it’s engine or coolant circulating) but it doesn’t last more than a few mins. On cold days I put it on when I’m fuelling up or other short stops to keep the baby and Mrs warm but that’s about all it’s useful for.


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[djjarvis]

My wife has it on her Touareg and I’ve got a similar feature on my A7. Neither have any additional heaters or auxiliary warming devices and both are fairly useless. They use the warm engine (not sure if it’s engine or coolant circulating) but it doesn’t last more than a few mins. On cold days I put it on when I’m fuelling up or other short stops to keep the baby and Mrs warm but that’s about all it’s useful for.


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A few minutes is all I was expecting too. I get about 30 seconds then it's cold.

I think it should be running the auxiliary water pump to pull more heat out of the engine into the heater matrix. Either mine doesn't have that pump or it doesn't come on in REST mode. Being a petrol it might not need an extra pump to make the heating effective on a cold start; the engine warms up quickly enough. But there are such pumps for sale to fit this precise car+engine!