My 1974 ford ranchero gt's heater makes my voltage drop from a 14.2 down to 12.1 or even 11.9 at times and makes it so i cant use my headlights and heater at the same time. this cant be normal, is it? i have a brand new alternator.d
And have your new alternator checked for PROPER output - it may make voltage, but not enough amperage.
And don't forget the voltage regulator, its connector, and clean case grounding. Since you have a '74, unless you're keeping it all original, swap to a newer solid-state regulator. All regulators through '74 require maintenance and adjustment; the solid-state units only need clean connections and case grounding. I did this on my '74 Squire, and was never happier after that.
When you have the blower running, grab the wires and see if they are warm. A worn or bad motor can draw and unnecessary amount of power. Water also tends to leak down from the cowl and drip inside, which could be why the motor would be bad.
After checking out all the above and fixing whatever is causing the current problem, I would install a relay so the heater runs off direct battery power. But then I am a big fan of relays wherever possible. Russ
