[findrivr]

Not a big problem...yet, but I can see that when I run the fan on high (now that the weathers cooling and I need to run some heat), the dash lights dim and, not sure, but maybe all exterior lighting as well.
It's all original wiring w/replacement of old ext reg. 63 amp 10DN to a 100 amp CS130 (PepBoys). Battery is about 6 mo's old and elec./start system exhibits no abnormalities other than also a very minor dimming of dash panel when I hit the brakes or hit the turn signals, but it seems to brighten back up when the alternator senses the load.
Seems like I hear a laborius whine coming from the blower motor (or squirrel cage brg's?) that is louder at low speeds than at full hi, so my first suspicion
is for the worst: access and replace the blower motor. Or, should I try the blower relay on the firewall next to the AC box under the hood? (I think that's it anyway.)
Or, if it is the squirrel cage brg's creating undue drag on the motor, would it be easiest to replace the cage first and see if that eases the draw on the system?
Seems like it wouldn't be a big problem if I never want to run the fan on high, but since thats not an option, I guess that other than at high rpm's, I may be working the life out of the battery.
Comments and suggestions greatly appreciated as I would expect this is a great time of year to discover those exquisite little inconveniences like a murdered battery or melted conductors, etc.

 

[John_Muha]

Since I can't hear it I'll just go by your observations. The blower just attaches to the motor shaft so it's not your problem. I'd attach 12 volts directly from the battery and see what the motor sounds like. If it has a laboring, slow to come up to speed, or or squeel sound replace the motor with a new one. Should be able to get one from the parts store. These motors don't wear down the battery when the car is running. The alternator keeps them going.

 

[Elree Colby]

When you installed the new alternator did you use the existing output wire?

If the blower is starting to drag and you run it below high speed you risk overheating the speed switch wiring and connector due to higher than design current draw, high speed current bypasses the speed switch. It is not uncommon to find the connectors melted from this condition.

 

[findrivr]

That sounds logical and consistent with what Elree says, John. I thought the blower motor and fan or squirrel cage were all one unit. Still, it sounds like a 'mutha trying to get to it via removal of the inner fender, but oh well.
Elree, when I replaced the alternator, I installed a new pigtail due to the conversion from ext. to int. reg., but that's it. The remaining third wire (I think it was brown) ended up backsplicing as per the wiring schematic posted by Wes Van at the 'Tech Ref' page on alternator change-outs of this site.
Another symptom (probably unrelated to the fan blower motor problem) I didn't mention before about the charge/elec. sys. is that when idling, I can actually see a minor, irregular interval of a moment of dimming that corresponds to the engine idle sound variation; almost as though every 30 revoltions or so (assuming an idle speed of about 600 for round numbers), one cylinder seems to miss due to an interruption or arc-ing. I would suspect the arc-ing to be from that tight fit next to the header of the third hole fr/front on the driver side. I have Taylor 9mm wire with a rap of heat insulation jacket on that rt angle boot, nontheless, there is a tiny bit of heat deformation (melt)on that one boot. Seems as if it was arc-ing to the header, I'd see a scorch or burn, especially since the headers are ceramic coated. Other than that, the distributor is a new GM HEI (Summit) and the block has less than 40000. Running a stock assy. with an Edelbrock 600 and a 3.36 REnd/700r4, I've suspected the possibility of a slight mis-fire due to the fact that I've not seen better than 13.5-14 mpg. I've thought of having it Dyno'd just to see if this would be a way to trace a firing irregularity.
Wow,..I sure got a ways off from the elec. sys. problem...any comments or suggestions, again, will be appreciated.
Thanks.