Ok so this is pissing me off to no end I don't know where to start to diagnose this problem or how to fix it. At night when I have the lights on the cars voltmeter reads around thirteen while I'm at speed but when I stop it drops down to around twelve, the signal lights slow down when I brake, and also the blower motor shuts off. If I turn the heater off and back on again usually it will kick the blower motor back on but not always, I've replaced the blower motor, battery, and alternator and it hasn't changed a damn thing. Does anyone know what direction to point me in?

did you check the relay and see if its clicking?

bad ground from engine to body?

I'm fighting a similar problem. just had to replace my Alt. due to a weak rectifier. (but you've replaced the Alt. ) I'm going to replace the engine to body ground and the wire off of the Alt. that charges the battery ( heavy gauge wire to the bolt on the back of the Alt.) as well as the 2 wire connnector... I noticed mine is busted up a little ($8 @ OReillys).
Doesn't the heavy guage wire off the back of the Alt. run down to the starter? Does anyone know if it is fused?
(sorry to hijack this thread, maybe it'll help us both out)
I saw this before I got a chance to search... guess I'll do that now.

Tony

ok so I messed around with it today and it seems the blower will turn on if its in the max AC, normal AC position or in the defroster position but not in the vent, bi level, or heater position... I may be dealing with multiple problems here but does this information help at all? also which engine ground and relay should i be looking at? I took a glance at all the body grounds i could see but didnt see any that looked like they were rusted or corroded...

does no one know? could it be part of the HVAC switch I dont really know how these work or what their purpose is, I was under the impression that it was to control the vents on where it directed the air and not turning the blower on in certain positions... can anyone help?

anyone?

You should be charging at 14.2 or w/e Running, I would check the wiring connections and test the batt, But seems like your alt ant putting out.
GL

time to get a multimeter and start doing some tests
if you don't have a multimeter,a $15 chinese cheapie
from radio shack,wal mart etc.will be enough.
start car and check battery voltage-should be around
13.7-14.5 if the alternator in working and wiring intact.
with engine running,turn on the lights and heater blower
-touch one lead of multimeter to a clean metal spot on
engine,other lead to good ground on body-if multimeter
reads more than a few 10ths of a volt ,there is a bad
ground to the body. do the same test from the batt neg
to body etc,etc-lots of tests that can be done
common trouble spots are where wires come off the
starter pos stud,(loose connections) bad battery cables
body grounds.other possibilitys are the bulkhead
connector at the firewall,and bad connections behind
the fuse panel(feel for hot fuses) does sound like you
might have multiple problems...

Ok so I think I fixed problem 1 the blower motor, last night I was screwing with the controls and found that if I pushed the ac slider inward to the front of the car the blower would turn on and this morning I took it apart and just repositioned the slider controls above the radio and I havent had any problems thus far but we'll see tonight, thanks for the replies maybe I'll get a chance tomorrow to look at everything with a multimeter, I'll post updates as I get them

So I found a black wire that was un grounded towards the front passenger side, ive since grounded it but havent seen any changes in the low voltage problem, none of the fuses were hot, but I did find something interesting, not sure if it makes a difference but if someone could tell me what this hanging wire is supposed to be to I would appreciate it...

No clue what that goes to but. For the blower motor problem Mine did the same thing So i took and sanded where a bolt is. OF course unbolted but got to where it was silver shiny like then use a wire and ground it to the frame and now it works like it suppose to. It could be the case with yours the blowermotor not grounding right. now for the low voltage. Did you tighten your belt on the alternator because sometimes if the belt isn't tight it will slip and cause the alternator not to work correctly under any kind of loads.

It sounds to me like all your problems are related to grounds that have deteriorated over time. It is imperative that all the engine grounds be clean and tight. Make sure your negative ground from the battery to the frame of the vehicle is clean and tight also. I know you may have checked them already but check closer just to be sure. Improper grounding can cause all kinds of funky weird problems.