I have a 1993 Grand Am and every time I turn on one of the defrosters, front or back, the car dies. Then when I go to restart it none of the electronics in the car turn on and it does not try to turn over. Then if I wait about 15 seconds and try again it will start right up. I think it is the alternator. What do you think? I need to get this fixed before winter.
Sounds like a possible short to me.
If it was the Alternator it wouldn’t die immediately. The battery would probably have to drain first…then it would die.
Yes, I think you should get it fixed before winter, too. You start with the wiring diagram for the dash, trace the wiring for the defrost controls wth a multimeter, and find where the wires are shorted.
The front defroster uses engine generated heat to clear the windshield
The rear defroster uses a heated electrical grid to clear the glass
All electrical problems start with the battery (including diagnosis of electrical problems) so start with the battery.
A problem that comes and goes in 15sec does not point to the alternator, it points to a battery or more likely a battery connection problem.
It seems your battery is so discharged (I think from poor connection or damaged battery) that it can’t handle the electrial demand from the rear defroster.
Now why operating the front defroster causes the same sympton may be that in addition to selecting defrost you are also selecting a high blower speed (also a high current demand)So you should be seeing the same sympton if you select high blow for defrost or high blow for cabin heat.