1976 CJ5 Heater Blower Switch Dimming Dash Lights

[Mike]

Evening, fellow Jeepers!

Wanted to run this by you guys. When I turn my heater switch on low, the dash lights dim very slightly. When I turn it to high, they dim pretty good, and the volt meter reads about 11, down from 13.8. This can't be normal (can it?), and I can't understand why they're dimming at all with a new alternator otherwise pushing a full charge to the battery. I can't see where a short could be, but that's almost how it acts, like a BIG draw. Any ideas? Thanks!

 

[dalefan88]

check and clean all your grounds. also wait and see what cj and the other good electrical people on her say lol.

 

[BajaEdition]

Dale is correct, Electricity runs down the outside of a conductor, so if you have corroded connections it will have a hard time moving as the Resistance is hard. OK not to get into deep theory let us just remember that if we up one of the 3 values we have to lower another. Hence we up the resistance (ohms) significantly so the amperage goes up to compensate droping the voltage.
if this does not help the next place to check would be switch, if you have several speed switch, check it as it actually will be a form of variable resistor. I uses resitence to lower the speed, and that means they work hot all the time and wear out.

 

[Mike]

Thanks guys!! Even though it's a new switch, it warrants checking! I'll also check the blower ground.

 

[rushpowersystems]

13.8 volts is low you should be at 14.2 - 14.5, I have posted a tech on how to do a voltage drop, it may help you with your situation.

http://www.jeep-cj.com/forums/f7/got-electrical-problems-do-voltage-drop-test-2961/

If everything checks out on the voltage drop testing then you will need to look into your alternator, just because it is new or rebuild does not result in factory performance. If the alternator cant keep up with the load the voltage will drop.