Suburban Problem

DC3

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Dec 9, 2008
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332
Location
Lubbock Texas
I have an '05 Suburban w/ 5.3L V8. Made a trip to another town the other day (120 miles one way). On the return leg, I noticed my AC wasn't blowing quite as cold as it should. I checked the pressure and sure enough it was low. Charged the system but it still wouldn't cool properly. While scratching my head, I get a "Charging System Failure" message on the dash panel. Checked the alternator and no output. Checked the battery and voltage was down to 12.1 V. Battery is a very recent Sears Platinum AGM battery and is not the problem.

Charged the battery manually, then took the Suburban to the shop as I was out of time to work on it myself. They found absolutely no problems. My charge of the AC system was fine. Alternator tested fine. No error codes set in the ECM.

Anyone have any ideas? Could the alternator having no output and battery voltage dropping to 12.1 have impacted the AC system to where it wouldn't cool properly?

Scratching my head over this one but then so are two mechanics.

DC
 
Replace the alternator, AND the regulator connector plug/wires....should be a single wire on it, to the L terminal.....

sounds directly to a job the other month on a buddy's friend's '03 something chebby pickup.....one bloody intermittent mother focker, but I caught the damn thing on the second chance, and FLIXED IT!@!!!!

:bomb::clap::lol:
 
Replace the alternator, AND the regulator connector plug/wires....should be a single wire on it, to the L terminal.....

Did you find it was just the connector at the alternator or does the entire connector/wire back to the next point need to be replaced. I haven't traced this wire yet. Where does it go from the alternator? Is there a handy junction point or connector in the wire somewhere downstream where it could easily be found?

After posting earlier, I remembered the original alternator failed last summer. I replaced it with what was supposed to be a high quality NAPA unit. That one lasted just a few weeks. The latest one has been on about 10 months or so. Makes me think now it's the wire you mentioned and not the alternators.

DC
 
Replace the alternator, AND the regulator connector plug/wires....should be a single wire on it, to the L terminal.....

Did you find it was just the connector at the alternator or does the entire connector/wire back to the next point need to be replaced. I haven't traced this wire yet. Where does it go from the alternator? Is there a handy junction point or connector in the wire somewhere downstream where it could easily be found?

After posting earlier, I remembered the original alternator failed last summer. I replaced it with what was supposed to be a high quality NAPA unit. That one lasted just a few weeks. The latest one has been on about 10 months or so. Makes me think now it's the wire you mentioned and not the alternators.

DC

I forget the type alt that was on this vehicle, but it had a square plug with 4 possible wire slots, only ONE of which was used, and it goes to the idiot light on the dash, it's marked the L terminal...your plug MAY have more or less wiring, I dunno but it goes to the regulator, not the output stud....
We took the alt to the shop here, and he put it on his machine and powered it up, and could not make the thing cut in/out, so sold us the connector, as when on the truck, I could make it cut out by massaging the connector, well on the truck the thing was HOT, not cold....and it did the same shit, of course, so on the second go round, the alt was exchanged with the alt shop, he was cheaper than NAPA/anyone.....only 100 bux exchg....instead of 130 bux....you see the owner of the truck is totally ignorant, I mean totally, NO worse than that even, about anything mechanical, forget electrical, all he can do is watch the fuel gauge....if that, wife saw him pull outta the driveway,and started crying, 'That man is DANGEROUS, I would NEVER drive with him...so he don't know to watch the voltmeter, much less it's meaning....

:harhar::trumpet:
 
Look at the - battery cable near the battery. There's a module taped to the cable that controls the alternator (generator battery control module). It's pretty common they crash. They're suppose to default to 12.7 V, but that doesn't always happen.
 
This probably has nothing to do with anything but i rented a 10 or 11? Suburban in Canada and freaked out. Looking at the volts gauge, it doesn't charge all the time, just when the computer feels like charging it?? I thought i had a bad alt until I looked at the gauge long enough.

My 02 Suburban's A/C doesn't blow as cold at idle for some reason. As soon as you get the revs above 1000 it's ice cold.
 
This probably has nothing to do with anything but i rented a 10 or 11? Suburban in Canada and freaked out. Looking at the volts gauge, it doesn't charge all the time, just when the computer feels like charging it?? I thought i had a bad alt until I looked at the gauge long enough.

My 02 Suburban's A/C doesn't blow as cold at idle for some reason. As soon as you get the revs above 1000 it's ice cold.

Jim, that's what this guys truck was doing, once alt was changed out, it stayed at 14.x all the time....maybe 13.5 by time I got 20 miles over to his place....

sounds like the Burban needs a freon top off....
 
Thanks guys. I could not find anything that was obviously wrong. I'm now 800 miles from home in it with no problems. I have a scan tool that connects to my Android phone via bluetooth and I am able to log data with it. The voltage with the engine running would typically start at about 14.3 volts and then gradually fall to about 12.8 volts before kicking back up to 14.3 and starting the gradual fall again. The needle on the volt gauge correlated with the scan tool readings. I don't remember the voltage being like this before the problem. It seems back then that the gauge never dropped below 14 volts.

I did talk to a guy who said the AC problem was directly related to low voltage when the alt had stopped and the battery had run down.

I plan to double check the connector at the regulator and may even replace it for good measure when I get a chance.

DC
 
OLD electronic fart here, I know about battery connections, and voltage drops, also any other wiring/connectors and corrosion .....

I don't believe a thing any scanner or meter in the vehicle says....

I believe my Fluke DVM and no one else....but like any test gear, it has to be smartly applied.....

for instance....dragging starter, engine don't turn....first check is for the obvious terminal corrosion....if not....I put the meter probes on the battery terminals, digging into the lead pretty good, get a reading, if less than 12.6 something volts....I get worried, try another person hitting the lights, note the voltage....if below 11 the battery is weak/discharged....if something more, it's a debate....try starting the car, IF it cranks by some miracle, I read the voltage and need see 14.8 if not, the alt/reg is at fault....

pardon my explanation of the procedure.....but it's been the same for some decades and never rong....

On board diagnostics are not in the realm of being accurate to ME.....

:drink:
 
check this out before changing anything. there's a reason they were only used 04-05, they sucked.
http://ryangottlieb.com/rvc.pdf

I read through that. Way to make something simple more complicated than it needs to be. This behaviour is what i experienced in the 11 surburban. I wonder how much longer it really makes the battery last and how much energy it conserves.

It certainly makes it hard to know whether the charging system is doing its job unless you know what mode its in. This is a case where an idiot light is more appropriate than a volts gauge.
 
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