New here, but I'm at wits end trying to figure out an electrical glitch in my 1994 K3500. Any ideas or input would be greatly appreciated.

Symptoms:

flashers do not work. Turn signals do.
When turn signal is on my speedo needle dances with each flash.
Radio sometimes will turn off then turn back on when using turn signals.
Same thing happens when I turn on wipers (intermittent especially).
Voltage meter does come up much when truck starts, have verified 14.1 volts with digital meter, but dash meter shows low voltage.

Once or twice when A/C was on everything went back to working normally. No malfunctions with volts showing 14 on gauge. Turned truck off, restarted and all my usual symptoms returned. Tried A/C on/off, but could not duplicate 'normal'.

Alternator and batteries recently replaced.

I'm wondering if I have a bad/weak ground somewhere?