NE1 ever upgrading wiring using a relay to the blower motor?

Before condemming the alternator, you need to make some tests. You along with many others, may be fighting deteriorating bulkhead connector problems, along with other connectors and wiring.

READ the Mad article which, down the page, shows an important, simplified diagram of the layout of these systems

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

which came from here:

http://www.madelectrical.com/electrical-tech.shtml

ON the diagram, follow the charging lead and battery feed as it comes from the battery, through the fuse link, in the BULKHEAD CONNECTOR , goes through the AMMETER, and encounters the IN HARNESS SPLICE, and goes back out the BULKHEAD CONNECTOR to the alternator

These are all important points that can fail. Even the "welded" "in harness splice" has failed. This is a splice, taped up inside the under-dash harness, that feeds the headlight switch, the "hot buss" in the fuse box, and the ignition switch, and a couple of other things. It is NOT fused, and they HAVE failed.

Get out your meter, or buy one if you don't have one.


FIRST, check for voltage drop in the ignition harness. Turn the key to run, engine off. IF you have points, they much be closed. Put your meter on the coil neg, and if the voltage is "close to battery," the points are OPEN. Bump the engine until this voltage is LOW

Next, put one probe on the battery positive post, the other on the IGN feed coming out of the bulkhead, going to the regulator "I" terminal or the "key" side of the ballast. Normally "dark blue."

You are measuring voltage drop across the harness and are hoping for a very low value. Anything over .2V is too much, over .3V means get serious and find the problem.

Your top suspects are the bulkhead connector, the IGN switch connector and the switch

NEXT start the car, all accessories off, and running at a good fast idle. Let the battery charge to "normal" (ammeter centered.) Measure battery voltage, it should be more than 13.5, less than 15. Optimum is around 14V AFTER the engine and regulator have warmed up!!

Now, turn on some loads the headlights, the blower. Prior to this, you need to have located some major points in the car wiring. You should clip a lead to each side of the ammeter and bring them out under the dash where you can access them. You'll have to unhook the battery ground for safety.

Identify the blower fuse for sure.

Now with the car running, loads on, measure some points and write them down, post back here:

Battery voltage across the posts

Alternator output stud to block.

Both fuse clips to ground for the blower motor.

Both ammeter terminals to ground from your clip leads on the ammeter

IN ANY CASE I would pull the bulkhead connector apart and inspect it for damage, corrosion, loose/ overheated connectors.