91 Suburban Voltage Meter fluctuation

[geodiggr]

Hi all,

1991 GMC Suburban, 1500, 350 (5.7), 4x4, Auto

I have this teensy problem...when I start the truck, most of the time, the voltage meter (in dash) will read around 13 (most of the time), then as time goes on, driving it around, etc. the meter begins dropping and reading lower, finally ending around 8. At that point (or any point when it's low) the AC compressor clutch begins to kick in to raise the idle. If it didn't, it feels like it would die. Anyway, I've checked the in dash meter vs. a hand held meter and at idle conditions my hand held meter is not reading as low as the in dash...but when I'm on the road I haven't been able to pull over and check it out either...

Anyway, suggestions are...bad battery, bad alternator, bad computer.

Would like to know if anyone has had a similar problem and/or can offer any suggestions.

Thanks,
Rick