Hello and Welcome -
My name is ***** ***** Sorry to see you have had a wait.
With this issue, for the switching the headlights on to cause the engine to die, this would indicate heavy draw / pull on the alternator / battery.
This can be caused by a faulty battery - not storing / holding its charge as it should / properly - this can be down to faulty / dead plates in the battery. It may seem ok - it may start the engine - but it needs to be PRO tested on a machine to check for the above.
The other cause can be a faulty alternator.. so that when you switch on the lights , its not coping / putting the correct charge out.... so that needs to be tested. Use a meter on the battery... when you running you should see normal charge - over 12v.. up to about 14.6 -- then switch the lights on.. it will show a drop but not much - and certainly not below 12v. If it drops to 12 or below, the alternator is failing.
Check of course your wiring and grounds - but the above is suspect and needs to be fully checked through.
As to the blower, that is likely a seperate fault altogether - it can be the motor itself -and usually is.. but - you should check the wiring again too for sure.
If you do have a wiring fault / short / damaged or burned wiring, then yes it will cause all your faults together.. that will take manual looking / checking up under the dash etc.
But do check the other items first to either ID the fault or rule them out.. and then progress to wiring checks as above if needed.
Let me know how you go..and / or let me know if you need anything further on this..
~>>~~>>~ Meanwhile now - Please do click on the "Exc / Ok rating" for me at this time.. "Thank you" in advance for that .
.. Note that you can get back to me anytime at all after doing the rating - it doesn't close you out --
Best Rgds, MIKE