When in doubt, try electrical tape.
On my '84 Olds Cutlass Supreme, my voltmeter gauge always reads a little shy of 13 volts. When I turn on the air conditioning, the gauge dips down almost to the "red" area--about 11 volts. Is this something I should be concerned about?
TOM: I wouldn't go running around the neighborhood in your pajamas or anything, Joe. There are plenty of other things to be truly concerned about. There's the war in Bosnia, world hunger, welfare reform, not to mention whether the Yankees are going to move to New Jersey. So in the big scheme of things, the voltmeter is not a big deal.
RAY: First of all, these gauges are notoriously inaccurate. In fact, the only reason you have one in your car is that GM probably got a deal on a half million of them at a flea market in late '83, and then-GM-President Roger Smith realized at that price, they were three cents cheaper than putting in clocks.
TOM: Even if the gauge is accurate, 11 volts may be OK if the air conditioner is on and the car is at idle. After all, you're asking a lot from the alternator to run the AC. So I wouldn't worry about it as long as the gauge goes back up when you step on the gas.
RAY: If the gauge doesn't go back up when you step on the gas, then you should have the alternator checked. Your mechanic can test the voltage AND amperage output of your alternator with a machine, and let you know if the alternator is really is weak. If it is, he can investigate further. It could be something as simple as a loose belt.
TOM: And if the alternator checks out fine, then this is a perfect application for the famous Click and Clack Black Tape Solution.
RAY: Just tear off a two-inch piece of black, electrical tape, paste it right over the gauge and keep driving, Joe.