ODD PROBLEM - please help - clueless!!!

Hi, I have a 1990 Pontiac Transport minivan that started doing something crazy not too long ago:

The battery dies at random is the bottom line. No rhyme nor reason. We checked all kind of stuff such as interior lights left on, etc. The alternator is fine and so is the battery supposedly. We took it to the mechanic and of course the next day it started fine for him - he could find nothing wrong; this is what i mean when I say randomly. It'll be fine for a few days and then u go to unlock the door and there's not even enough juice to turn the power door locks so we have to jumpstart it and then it's good as new until it dies again...

Anyone have any ideas or ways to troubleshoot this kind of problem? The van still runs great, it's such a shame this is happening.

Another problem that now exists has to do with the AC/HEAT. I know the AC and Heater work fine; the problem is that the blower isn't working. You hit the max button, and u can hear the unit engage, but it doesn't blow out the vents! Bad relay switch or something.. Any ideas on that one?

Thanks for your help!
Mike
sdsumike619@hotmail.com

the "convenience center" you speak of - I don't see anything under the glove box - how do I get to it? In another post you said something about some connections behind the positive terminal of the batter, would that apply to the van randomly dying?? It's driving us nuts

I understand you come in the morning and the battery is dead..is that it? If so, disconnect the battery and install an ammeter to see what kind of load you have..and then start removing the fuses one after another...
easy "no see" culprits are the door locks actuators that say on, rear window defogger, ..
If if dies "on the go" that is more puzzling.
I also understand you do not have that blower running?.. Time to test the motor: easy things first!
Just browse through the scanned pages here if some are of any help
www.avigex.ca/xport

it'd probably help if i knew what an ammeter was before I were to install one... and what do you mean by removing the fuses? what does that do? And the door lock actuators? what are they, how do I see if they're causing the problem?

The van doesn't die after it's been on, only after it's had enough time to have the battery drained, and it isn't always, it's random, never know if it's going to be dead or alive when we get in it =(

Testing the blower motor is "easy" ??

Did you see my other post about the "convenience center?" Not exactly sure what you mean when you say it's under the glove box, I don't see anything under there :(

Thanks for your help,
Mike

Yes.ok. Your battery is drained to emptiness on a random basis: I guess your battery is in good condition so not the fault of the battery, cause a shorted battery cell will do that kind of trick, but this applies normally to batteries at least 5 year old.
AN ammeter allors to read "current" (not voltage, this is different) flowing through a circuit. THis is a basic tool for all even amateur electricians and can be procured well under 20$. WHen the car is turned off, there should be NO current flowing from the battery to the car - except an insignificant trickle just to keep the computer memory alive _ .
One can measure that by disconnecting one of battery poles, then reconnecting the circuit through the ammeter. DO NOT ATTEMPT to start the car in that condition. Leave the ignition key OUT of the car. All doors shut! GLove box shut! All lights off! Ammeter should read ZERO. But if your battery runs dead, something draws current when it should not.
If you read some current, (a 3 amp current will run the battery down in 20 hours, but even in 10 hours it will not start the car even if it can turn the lights on).
If there is some measurable current , then you can start removing the breakers and fuses that feed the different circuits of the car to find which one will cut the unwanted feed. I would suggest - if you have power door locks - to trig them locked and unlocked to see if sometimes the current stays, and sometimes not.

Ahh. testing the blower fan: check this out:
www.avigex.ca/xport/heaterrelay.jpg
and tell me you have the same setup (97 and onwards have internal (cabin) fan but the low 90's are eternal....mmm...no, external!
It is "technically" easy to remove the plug that feeds the "blower motor" and to feed 12 V directly to the motor with 2 small wires. NOw, this may be a little (I.m polite) "physically" difficult though because you have a lot of stuff to battle with to reach it...but given the fact your motor will not run at ANY speed, I'd give it a try.
Ahhh.. on the '93 ...apart from cosmetic change, this is the same - the "convenience center" that contains the "low speed heater relay" is hidden, way back low, under the glove box area, close to the firewall.
www.avigex.ca/xport/convenience_center.jpg
the low speed relay acts on ALL speeds, even the high, because it feeds the heater switch and IF YOU HAVE a rear heater fan, it will not work either! THIS IS A SERIOUS CLUE. One other relay just beside is physically similar and you can switch them for a try.

now how exactly do I GET to that convenience center in my 1990? It's not exposed from what I can see under there...Unless maybe i'm looking at it haha...

I don't think my van has a convenience center - does anything have to be removed to access it? In the diagram, it appears to be directly below the fusebox under the glovebox, but I see nothing down there...

I played with the fuses, and the only thing I could get to work again was the radio/clock (that had stopped working as well) but now it works..

A friend is bringing over the meter to try what you said

"then you can start removing the breakers and fuses that feed the different circuits of the car to find which one will cut the unwanted feed. I would suggest - if you have power door locks - to trig them locked and unlocked to see if sometimes the current stays, and sometimes not."

I know how to remove the fuses, but what do you mean by removing the breakers?

Thanks again..
Mike

I wonder where they put it in 1990..because there more that the fuse box in the glove box...
'bout breakers: look at the picture in the link for convenience center: there are breakers, smaller than the relays, they are thermally activated instead of blowing so they reset by themselves after a while is the is an overload. They can be pulled out to cut juice to the circuit they serve....I'll look back to my '93 transport for the convenience center..I remember is is way down back near the firewall, much farther that it looks on the drawing...
www.avigex.ca/xport/cc1.jpg www.avigex.ca/xport/cc2.jpg
..the plastic "bulge" must be removed first..it is hidden behind that. I got there once to transfer the power windows circuit so they can operate even with the key "off"...

Well here's an update so far.. We had a friend come over with an ammeter, but it was an amprobe he said, so it wasn't the right type so we couldn't quite do the battery test that you said to do..

With regards to the blower motor, he tested a bunch of things to make sure the motor was getting juice, etc,,, then finally, he just hit the darn thing with a hammer and voila - it started blowing. He said that the motor was just stuck perhaps, so we left it on and were talking and then noticed that it went dead again, so it is definitely the motor that is bad.

Next question - have you replaced one before? Is it a difficult job? It looks as if we just unbolt it and it's off, I'm hoping this is the case?

I think I see the plastic bulge you're talking about, there's some bolts that hold it on I think, will try and see if that is it tomorrow in the daylight..

Another thing my dad wanted to know about was where the sending unit for the oil gauge is? Sometimes the gauge doesn't register and he thinks it's the sending unit but we don't know where it is...

Good...problem identified then. Yopu remove the motor and impeller together by removing those bolts on the metal plate around. You might get the complete unit just like that at the scrapyard. The problem is probably one winding is cut from the "commutator", a set of small copper plates that make contact with the brushes one after another . Very often, one plate connection woth the copper wire is corroded or cut so when it stops on that plate, it will not start again...with the technical hammerblow, it may have rotated just a bit enough to make contact with the next plate.....
senna95 did change the motor
http://www.automotiveforums.com/vbulletin/showthread.php?t=372918

SO now, the question of the low speed relay is over.
What age is the battery?

The oil pressure "sending unit" is front of engine (facing right whell well), next to the oil filter; on the 3.1 of 1993 is just an on-off pressure switch connected to the needle..so it does not really indicate the pressure: it just tells that there "is" a pressure. Not sure if '90 was more sophisticated....The 3.8 has a real pressure sender.

...YOu see from this other post you have entered that there are several ways the battery will be drained. One easy culprit is the rear window defogger...the "relay" is an electronic device with a timer and it is known to go wild, and this will drain a battery in a few hours. This timer as well as the breaker are both in the convenience center. I'd remove one on them - either the breaker ot the relay ..and see what happens next......NOtice that if the RWDefogger turns on, the LED light on the button should be on to, but if like my car, I can hardly see if it is illuminated even if I look for it, so it can go unnoticed..........