dash message check guage for battery- bad alternator?

[89 lebaron]

vehicle is 1989 lebaron 2.5 liter turbo

Have a 90 amp alternator. When I drive and especially put on the air conditioner the check guage comes on and it shows the battery guage. The battery is tested and good. I don't think need a 120 amp alternator. is it just a bad alternator? Or do I need 120 volts? The alternator is about 2-3 years old. The car is not driven a lot.

Thank you

[jamesslcx]

89 Lebaron, I love those cars! First thing is to check you wiring related to the charging system for a bad wire or loose connection. Check voltage at the battery with the engine running. If low it could be the alternator or possibly the voltage regulator. Hope this helps.

[TMODZ]

had same problem it was a bad sending unit