# Auxiliar heater not working T7 Hybrid

**Source:** https://vwcaliforniaclub.com/threads/auxiliar-heater-not-working-t7-hybrid.59237/  
**Posts:** 7

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### S — 2025-07-29T19:15:02+0200 (Jul 29, 2025)

Hi Guys,  
  
May I ask how the auxiliar heating system works to you? I tried to set it immediately , permanently, with the charging cable connected, disconnected and also with the external power connected to the electricity socket but I cannot see it starts heating but only cooling.  
  
I heard a noise just at the beginning like it would start but less than a second and that’s all.  
  
Thanks!

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###  — 2025-07-29T19:46:45+0200 (Jul 29, 2025)

Have you set the temperature?  
It works really well, I believe it uses the engine battery so worth checking that is fully charged.

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### S — 2025-07-29T19:59:03+0200 (Jul 29, 2025)

I set the temperature to HI but it doesn’t work. Thought big battery shouldn’t be related as you can plug it to the power socket and in theory is enough.   
  
The sales guy told me if the interior or exterior temperature is hot it will not work as the thermostat is doing its function but setting it to HI I believe has to work.

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###  — 2025-07-30T08:42:22+0200 (Jul 30, 2025)

Interesting perhaps there is an ambient temperature above which the heater will not work.   
You may have to try when it is cooler.

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### S — 2025-07-30T09:12:57+0200 (Jul 30, 2025)

Maybe but I thought if you set max temperature it should work even in a hot environment like climatronic

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###  — 2025-07-30T09:19:29+0200 (Jul 30, 2025)

> [Sanacar said:](/goto/post?id=755257)
>
> Maybe but I thought if you set max temperature it should work even in a hot environment like climatronic
>
> Click to expand...

A. Try in the late evening.  
B. Have you got at least 1/4 tank of fuel? In previous models the Parking Heater wouldn't fire up if there was less than a 1/4 tank of fuel.

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### S — 2025-07-30T17:33:09+0200 (Jul 30, 2025)

The place where I am even evening the temperature is high and I’m not sure will work.  
  
About the tank is at 46% but I’ve been at the dealer this morning and his Diesel Cali heating system did not work like mine, therefore I would assume is a thermostat reason. I’ll test in a couple of weeks that will visit colder areas.  
  
Thanks!

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