heater high-alternator voltage drop

heater high-alternator voltage drop

Postby jcbgmz [OP] » March 17th 2016, 6:58pm

Hello all. I thought I might throw out a few ideas and maybe get some feedback before I start cowboying my way through the Stro's electrical system. Along with various minor odds and ends that dont concern me much right now not working right on an 02 work van I have one particular problem that causes concern. When the front heater/ blower only is on the voltage drops low enough for the battery light to come on briefly and constantly back and forth to normal. Less than a month ago the battery, starter, and alternator were checked at 3 different parts stores. All were good except oriellys said my battery was bad which I don't believe because it holds charge overnight etc. At 12.6. I have little faith in these clowns testing things because I brought an ignition control module to be tested and all 3 said it was good. At autozone I had to show the severely hungover lady how to do the test which I found out how to by looking at the screen she was staring blankly at. Needless to say the only possible thing that was wrong at that time was the module that was suposedly good.

There are absolutely no issues starting whatsoever. The only time anything happens is when only the front heat is on. I had replaced the blower motor a couple weeks ago but not the resistor which I know needs to be done. I don't have much, if any air on the 2 lowest settings but did before I changed the blower. This problem started just the other day. Code always comes up alternator terminal F. Even before I messed with anything a month ago this code would show. When I scan with heat load off no other code shows. When I scan with heat load on terminal L comes up, which makes some sense to me.

I believe the following probably to be unrelated but worth mentioning. I changed the thermostat a couple weeks ago and had to cut the 2 ground wires because i couldnt get the lug off the housing bolt, which I replaced with a new one. I believe one of the grounds is from the PCM, and the other one from various sensors etc., like MAF, ignition control module, and a few more. One wire was a 14, and the other one a 16. This I thought strange but it's original wiring. I had little resources at the time so I used a single 10 Guage wire to splice both of them terminating with an aluminum lug. All I could find for copper 3/8" hole was for 4 guage. Like I said, my thoughts are that this is probably unrelated but if someone wants to throw a comment in I would appreciate it. I plan on improving the connection very soon because it seems a little hillbilly.

Going back to my immediate concern, what does anyone think could be the issue with the alternator seemingly not doing its job? Thank you
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Re: heater high-alternator voltage drop

Postby jcbgmz [OP] » March 17th 2016, 7:33pm

One thing I just remembered. Now I had noticed this a few weeks ago before I changed blower. The vacuum line coming off the engine to a splitter was disconnected/rotten. I know one 5/32" goes to the ball on the bottom of the blower area. But where does the other one go?. I just capped it off for now because I can't keep one of them connected to that ball and I don't know where the other one goes.
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Re: heater high-alternator voltage drop

Postby Lumpy » March 17th 2016, 8:40pm

Lots of wading through that initial post... :poke:

Does the voltage drop problem occur when the fan is on HIGH? Or does it occur when it's on one of the lower settings? Or does it occur on any fan setting?

Unplug, clean and replug your fan connector single terminal AND your high blower relay socket. There may also be a fan ground screw in your year model. It's a simple, self tapping screw that's obviously grounded to sheet metal near the fan. Unscrew, clean and re-install that connection.


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Re: heater high-alternator voltage drop

Postby jcbgmz [OP] » March 17th 2016, 10:40pm

Thank you sir. I tend to not proofread and type thoughts as they come to me! Sorry for the blasting.

Drop occurs on all settings but the lower 2 seemingly don't work or don't work at all. Hard to tell. I'll give what you suggested and post back. Might not be for a couple days.
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Re: heater high-alternator voltage drop

Postby Lumpy » March 17th 2016, 10:52pm

I think it's pretty much narrowed down to either the blower motor, or the wiring TO the motor. It's not uncommon for the blowers to fail. A little tricky to install new ones, requires a tiny bit of cutting. But not rocket surgery. Just plastic surgery.

But be sure all those wires and connectors look clean and well connected to your satisfaction before buying a new blower.

Test the blower, I suppose. Rig up a fused (+) lead from the battery to the (+) terminal of the blower. If it seems to come on then and spin at the appropriate speed, but spins lower with connected through all the stuff in the van, I'd suspect wiring and connections rather than motor.


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Re: heater high-alternator voltage drop

Postby kennysmoke » March 18th 2016, 1:34am

I've owned 3 Gen II's, a '97 AWD, a'01 AWD and an '03 AWD... I've had similar issues with the Alt voltage dropping with the fan being turned on... a few times it was the fan speed resistor and a couple times a bad bearing in the blower motor binding the fan and causing an excess draw... look for this as well melted connector at the resistor....

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Re: heater high-alternator voltage drop

Postby jcbgmz [OP] » March 18th 2016, 2:11pm

Thanks for the info guys. After seeing many posts of the sites heavy hitters I have learned mucho. I cleaned grounds, tested what i could, and installed a new resistor. Heat fan worked good after but still voltage drop. Got angry and said screw it and put a new Bosch 105amp alternator in, and no more drop. I will see if the issue comes back and then I'll know if my impatience was good or not.

Also to my other question about the vacuum lines that split and one goes to the ball under blower motor and the other goes to? Any suggestions?
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Re: heater high-alternator voltage drop

Postby kennysmoke » March 19th 2016, 2:06am

Go here....

viewtopic.php?f=34&t=14502

Read this thread... all the info you need is here... Swap out all the **** plastic lines with vacuum tubing,,,
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Re: heater high-alternator voltage drop

Postby Lumpy » March 19th 2016, 2:25am

Silicone tubing. I used to get weird codes about once a year with rubber. Even more with those hard plastic things. Silicone's been in place nearly 4 yrs now. Haven't had to replace, shorten, snip, gorilla snot or anything.

And they come in purty colors.


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