Corsa Auxiliary Heater Issue

I had something similar with my Corsa; the ventilation was off, and the heat control was erratic. Check for a coolant leak first, then the blower motor resistor. It might be something simple.

When you say 'similar,' did you also get an error code, and the parking heater wouldn't start? Or just temperature fluctuations? I really need that heater working!

Yeah, exactly that! Parking heater completely dead and an error code. I ended up taking it to a workshop. They fixed it quickly, and I didn't want to risk making things worse!

Sounds like I'm going to the shop then. The mechanic confirmed it's a defective glow plug, costing 440€. At least I know now!