my wifes 95 legacy postal dont charge under load. lights and radio it charges fine, turn on the a/c forget it 12.2. swaped a good alt in and the same thing. any sugestions?

is the A/C cracked up maybe or you feel certain it's the charging system?

 

battery and alternator connections/connectors are good and not weak, warn, or dirty?

 

i'd connect jump cable to positive battery and the alternator post and see if the symptoms subside. on my own daily drivers i've ran straight heavy gauge wire between those two before but that's not advisable electrically speaking, should be fused or something. but it bypasses some of the possibly old wiring.

Are you talking when it is just sitting idling, or while you are driviing? My '96 and '00 if left to sit say stopped at a long light with the brake lights on and a/c on max the voltage slowly drops and will get as low as around 11.8V. While driving or even slightly above idle it is not an issue to keep it up around 13.3V or so.

driving or idling it dont matter. i had to go jump the car when she was working, and she was useing the a/c. this is why the new batt. and terms. all connections are good and clean. i will try jumping it when she is done with work today and let you know what happens.

Edited July 10, 201015 yr by rtcaravan

If you are taking the voltage readings while the engine is at idle speed then you shouldn't be too concerned about it. The voltage readings should be taken while the engine is running at around 1,500 to 2,000 RPM and preferably at the alternator output lead. You should see between 13.5 and 14.8 volts if the alternator is working ok.

 

You should also check the voltage between the alternator output lead and the positive battery lead if you suspect a problem in the wiring. There should be no more than a .2 volt difference with a good load on line. If it is more you need to check the wiring for a problem. This line is fused for protection against a possible short and bypassing the fuse is not a good thing unless you are just doing a test. Doing the voltmeter test will show up any problem on the lead and is safe to do.

Unless you are check electrical faults under load, your multimeter can lie to you. Check out the TesLite Leds. www.brighterideas.com.

 

They allow you to load a circut. Dan also has some good training videos on his web site.

 

Larry