voltage dropping while turning on rear demister

[vinnY]

so my car runs fine with a constant 14.2-3v but when i turn on the rear demister the voltage drops straight to ~12v

now i know this isn't good, only started happening recently so hopefully i've caught it early

anyone know what the problem might be? busted alternator? bad ground somewhere?

[CRXer]

Grounds will produce a high resistance joint,so less current,less voltage drop.

Go get your alternator load tested,doesnt cost much,doesnt take long.

U got some serious regulation issues there

[vinnY]

will probably try and find another alternator to whack in and test it out

before that, anyone else have any suggestions on what it it might be?