hah.... you make it sound easy! and now I'm feeling like if I don't replace the cable I'll be cheating or something! I think one other way to 'verify' is to make a new large gauge cable and run it from the alternator B+ post to the shunt (like run it under the car, or over the car, just as a test) and see if I still have voltage drop; if not then I'll correctly install the new cable. If I do still have a voltage drop then the new cable isn't the cure after all...
You could route it along the frame together with the starter cable. You can re-use most of the existing mounting attachments. Only part that will not look stock will be the routing along the antisway bar. Once you see the starter cable that goes to the shunt this will be easy to figure out.
guys... a bit of a revelation this morning... I went to the warehouse quite perplexed by the whole voltage drop and something dawned on me - I hadn't checked the voltage of the battery with the car running AND THE AC CONTROLS OFF. Well... within a minute or so the voltage of the battery matched the alternator at 14.1. SO... at least now I know it's very likely not the cable. BUT... unfortunately this means I still don't have a true grasp on exactly what is going on. As I think about it my first inclination is to check the evaporator motor; it runs very well and doesn't make any funky noises. Maybe the resistance is up? maybe the wiring to that motor is dirty or fouled up? The only other consideration is the upgrade/modification I did to the radiator motors - installing the Spals with new relays for each. Obviously with the test I did this morning with the AC off both rad fans were not running (the right fan would only have turned on when the oil got hot enough but the car wasn't on long enough for that) Any thoughts on the matter are welcomed...
I dunno that acceptable voltage with the AC controls off indemnifies the cable from being the problem. It just means that reducing the load on that wire means it's now sufficient to carry the 'no AC on' level of current. If anything, having the voltage drop across that wire with the AC on kinda points to it as a culprit. I'm a fan of the idea of running a temp wire of a higher gauge in parallel with it and seeing how that goes. If a bigger wire alleviates the low voltage situation, then that's your smoking gun.
Guys - a little update: So with the temporary 4 gauge jumper wire in place (16’ with new leads on both sides) there was no difference in voltage at the battery, and the same voltage drop was present. However, I the put in a new voltage regulator on the alternator and I do believe it made a difference. With the car on and idling (all-be-it poorly) voltages were: - 14.5 at the battery and nothing on - just <14 with AC on full - 12 at the clutch with AC on full I did check the resistance of the new compressor/clutch and it was ‘normal’ - I think 2.5 ohms or very near that. I still have not adequately checked the 2 AC switches (snowflake and fan speed) but that’s a must As soon as I get another chance I’m going to refill the AC with Freon so we can do a ‘test under load’ if you will. I’m feeling like this may be ‘the normal for my car’. Per several of your comments I realize that this wiring is 46 years old and there just may be some increased resistance in the wires without obvious visible changes in the look of the wire. I may prophylactically change ‘the big wires’ just to be safe, and I will go through the relays and fuses again, although they honestly look…fantastic. I’m really trying not to run a relay for the AC clutch, but that is what I may end up doing if I still get slip and catch at the clutch. More to come…. Cheers!
