starts ok shows 14.7v then it will go down to 12.9v varies between the high and low voltages. alternator going bad or is it normal??????

 

Sounds pretty normal to me - I would be more concerned if it stayed at the high or the low. Still the factory battery?

 

I don't have an Uplander, but my voltage stays constant at a bit over 14 volts all the time.

 

Since its winter, I'm thinking that gaftop is likely running the heater in his Uplander...when the floor vents are selected, the compressor and cooling fans will run on and off...fans on, 12.something volts...fans off, 14.something volts...

Just like our Uplander....

 

not factory battery and i'm on the gulf coast so, not running heater running the a/c.
thanx for the replies

 

Running the AC you will notice it especially when driving in town. Our lights will quickly dim and come right back when the fans kick on. Sounds like you have no worries!

 

2007 chevy uplander ,,, cooling fans will not come on when you turn the ac on .... if the ac is off the fans work ,,, replace almost every sensor and switch ,, any ideas ????

 

Cooling fans don't come on at all when AC on? In our 2008 they don't come on all the time with the AC on - they cycle on and off while you drive.

 

The Voltage on my 2008 Uplander has done the same thing since it was new. I think this is normal for this vehicle, I haven't had any problems with mine. As a precaution, I replaced the Battery this winter, we had unusually cold weather.

 

My Alternator breaks when it reaches 141K not to mention the idling when in winter time, start the car early to warm us.(Uplander 2006).Hope this helps for the lifespan of alternator.