I have a 92 RS with factory AC and when I bought the car it was missing the suction and discharge hose from the AC system. I purchases a new set of hoses and a receiver drier, installed and charged the system. Once the system was charged and I turned on the compressor, the alternator will stop producing voltage and no longer charge the battery. Once I turn off the AC and leave the car running for about 5 minutes, the alternator will begin charging again until I turn the AC back on and it’ll once again stop charging. When activating the AC the car will slightly idle up and the alternator will begin to up its output for maybe 2-3 seconds before just ceasing to charge. So a few questions. How many amps should the alternator be outputting at idle with just the blower motor and fans running? With a lab scope and amp clamp at idle, my alternator is outputting 70-75 amps with just fans, blower and radio. That seems excessive considering the it’s rated at a max output of 105 amps. The alternator is acting as if it’s becoming over loaded with the additional amperage draw from the compressor and turning off. Also, the alternator is becoming VERY hot which is leading me to believe it’s becoming overloaded. Is there a drop in solution for a higher output alternator? 130amp possible.

 

I am in a similar problem but A/C related.
I had my alternator, 12si, rebuilt a week ago. Had the voltage drop from about 15 to 13 volts in 60 miles of driving with headlights on.
Stayed that way until car had sat at a car show for about 10 minutes & it went back to near 15 volts. I took the alternator back to the repair shop & he placed it on a test machine and forced 100 amps against the alt as it spun for over an hour & no failure.
In my case, I had changed nothing & the alt last year travelled over 130 miles in the night with headlights on - high & low.
My battery dropped to 9 volts because I left the dome light on. Recharged the battery.
Rebuilder suggested that the battery may be the cause as he experience same problem with a customer whose batter carried proper voltage & a load test passed. But customer said alt dropped to 13 volts. He installed two of his own alternators & same volt drop occurred. Cust replace the battery & problem solved,
I will wait until next out of town, at night to see if problem reoccurs but that is a month away.

 

If that amp reading is accurate,that is WAY too much current-one of the fan motors should be smoking.My guess is the alternator is faulty-cs130 is about the worse alternator GM ever made and it may have a shorted diode(s) or other fault.

 

70 amps is WWWWWAAAAAAAAAAAAYYYYYYY too much current for the conditions you describe. The fan should be drawing about 30A, the compressor maybe 5, and the blower maybe 20ish if it's on the highest speed.

I think I'd start by finding out where all that current is actually going, BEFORE worrying about the alternator. Not saying you don't need an alt, don't have an alt problem, or any such; it may turn out, upon actual troubleshooting and data gathering, that you do; just, you've got some other problem that needs attention FIRST.