A car with blown headlights is also drivable, doesn’t mean you should drive it or you won’t get a ticket if you’re driving at night.
Correct. But in this case your headlights, HVAC, and turn signals are still working. (Even if you can't hear the turn signal indicators.) So I think it is perfectly legal to still drive it.
But, it still has to be fixed. The big deal is that it doesn't leave you stranded requiring a tow to the service center.