Install Stand Heater | Retrofit Cabin Heater

Hello,

I'd like to find out how it is with retrofitting a Webasto auxiliary heater to the Climatronic system in a TDI PD 150. Has anyone had any experience with that?
What does something like that cost?

Sure, here is the translation of the text from German to English:

'Another question:'
'How easy is it to retrofit a GRA (presumably referring to a specific type of system) to a TDI Highline manufactured in 03/2001? I need more detailed information.'

Thank you in advance.

with Andre