Just a guess, but doesnt the car get its heat from the engine? On almost 99.9% of vehicles (including new cars), the heat comes from hot coolant going through a heat exchanger in the air distribution system, and coolant doesn't start moving until the thermostat opens up...

Some cars do have electric heat (I'm just learning about MB's), but you probably won't get heat until your engine is up to temp.

If you have auto climate control, you might try running the wheel up & down a few times to clean the contacts.

I'd also like to know what's "flickering". If the engine isn't up to temp, the climate control system might be turning on & off until it starts getting hot air...

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A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.