Hello everyone my Name is Mike. I have an 01 Dodge 3500 w/453000 miles. Having an issue with alternator not putting the required voltage to the batteries.  after numerous alt exchanges and no improvement Im at a loss.When the alt is not putting the required 13.5 volts the a/c compressor quits working.

 

 

What voltage are you seeing? The out put voltage will vary depend on temprature. The PCM reads the temp sensor under the drivers battery and regulates the voltage. I have seen mine go from 13.2 to 14.2. The colder it is the higher voltage.

The voltage varies from  normal to zero but most of the time it hovers around 12.As soon as it drops off the required 13.5 volts the a/c clutch disengages.

How are all your electrical connections especially grounds?  Might try cleaning them up. 

 

I'm going to throw this out to see if anyone knows.  Is it possible the pcm is not regulating the alternator correctly or possibly reading a wrong temp from the battery?

 

L8tr

D

The charging system is extremely simple.

 

Green wire is a variable ground controlled by the PCM.

Blue wire is a key 12V lead.

 

So if the fuse is cracked it could randomly charge and then quit. I've seen weird things happen with fuses cracking and not blowing out. 

 

This article shows how to test it.