VW Golf IV Climatronic: Coolant Temperature

Hello,

I'm currently in the process of upgrading my manual climate control system to a Climatronic system.
During a function test, the control system behaved strangely; in automatic mode, only cold air comes out (regardless of the temperature setting). However, if you only select the ventilation vents for the dashboard, warm air comes out immediately.

Using VCDS, I noticed something unusual with the coolant temperature reading in the control module; it's showing -99°C for me.
I suspect this is what's causing the behavior, but where does the control unit get the coolant temperature data from?

I am grateful for any help, austrogolf.

Good morning.

While reviewing the label file, I noticed the following entry:
010,4,Coolant temperature, -99.0 °C = Not relevant/unused (e.g., in VW Golf/Jetta (1J)).

It seems the MWB (maximum weight before) is not the deciding factor; so it seems my StG (Sturmgewehr) is malfunctioning!

I am still grateful for any tips.

Have a nice day, Austrogolf.