I'm thinking I need to rebuild my alternator (yeah!). When I'm driving the car the "G" light comes on if I turn on the AC. No problems when it's off. I checked the voltage at the battery and it's 13.8v when the car is at ~1000RPM (but the AC was not on). The manual says to check the belts and I did that and the tension is fine in them. Is there any way to check the alternator output while it's in the car (or did I do that by checking voltage across the battery?). I can check it again with the AC on and see what the voltage is. The light is very, very faint.
Having the A/C on just drops the revs a little. Probably enough to have the 'G'/alternator light come on at an idle. Either raise the idle just a bit or ignore it. As soon as you accelerate, the light will go out.
I had a Chevy many years ago that's alternator light would glow when the heater/AC fan was on. It would get brighter as the fan speed was increased. It was caused by a short in the instrument wiring. This may be what you are experiencing, just a thought.
Well, that's not quite true. The electrical demands of the car go way up when the AC is on. The AC clutch is an electromagnet that requires power, the blower motor is on and most cars radiator fans are activated when the AC is running to make sure air is pulled over the condensor. These are all power hungry accessories putting a load on your alternator and voltage regulator and fuse block (a potential issue with Mondials and 308s). I'm not saying you need an alternator, but a lot more than just compressor drag could make the light come on!
Voltage is irrelevent. You need to check the current output of the alternator. You can check on the cable behind the alternator, or at the battery. I would like to see 20-30 amps at idle(depending on alternator). maximum out put should be on a lable on the side of the alternator, and is achieved at approx 2500rpm(engine) quality rebuild of alternator costs about $350.
How exactly do I check the current? Can I use my multi-meter or do I need something else? FOH uses a place close to my office. A local guy here had his done by that same shop for ~$150. It's not the rebuild that's the issue, it's getting the damned thing out.
You can use you multi-meter, IF you have an inductive clamp and your meter can handle 100amps+ (dont want to blow the meter). Another alternative is a simple clip on amp flow meter, snap on,mac, matco tools all supply them as do (i suspect) sears and other tool outlets. This is a simple gauge you clip on a wire and the needle moves in the direction of the current, and shows the amount. (think of current as water moving in a river). with a full charging systems tester you are able to put load on the battery and therefore fully test the alternator and charging circuits. As for getting it out!, its not to bad, but for me to help on that you would have to fly me out, or ship it here. I cannot do skinned knuckles over the internet. Sorry!!
Most auto parts chain stores will test your electrical system for free, if you drive your car to the store. Call ahead and ask. They will hook up their machine and load test the system and give you a quick dianosis.
There you go. I didn't think of that. But that should work. Make sure they are not colour blind, (black-red...etc)
thanks guys, I'll try one of those this week. In fact, I'm betting an electrician at work has an amp pro or amp flow meter I can use. Thanks again. Regarding removing the alternator, it looked quite involved. I seem to remember frame parts in the way, headers in the way and maybe the cam belt covers as well?
