hi voltage

my volt gage is really jumpy and always at 14 or higher and jumps down then back up when i turn the heater fan on any one know any thing about this or have this problem to

How far low?

12 and back up a little over 14

Be prepared for your alternator to go out soon.

Looks like it is on its last legs.

BTW, don't crank your defrost and fan up full blast when you are idling.

It does nothing to get your truck warmer and it seriously is hard on the electrical system.

But even so LT, if you are sitting in traffic, headlights on, fan on high with/without A/C, the alternator should be able to stay above the engine off voltage of the battery. If it doesn't, there is a problem that warrants inspection.

But even so LT, if you are sitting in traffic, headlights on, fan on high with/without A/C, the alternator should be able to stay above the engine off voltage of the battery. If it doesn't, there is a problem that warrants inspection.

I understand that, and it is probably a weak alternator on its way out.

All I was stating is that it is really hard on the system to produce enough power at idle for that kind of load.

I see a lot of people that always crank there defrost on, their fan on, their rear defrost on and then find one cold day that there battery charge is low.