A month or so ago, my battery would drain completely after every time I got out and let it be for any length of time. One day, I was standing there talking to my friend after I had shut the car off and gotten out and set the alarm, the blower motor turned on by itself. I got in the car and turned the key on and it went to low setting (where I had it set on the heater controll unit. Turned it off again and waited around, sure enough, it came back on again. I noticed when the car is on and I turn the controll unit off the blower motor goes to the highest position (same as when the car is off) but when the unit is on, the blower motor acts normal and goes to the set setting. So I pulled the fuse to the blower motor (big maxi fuse under p/s floor). Anyways, that seemed to fix the problem (of course my blower doesn't work now, so no AC or heater for now). But anyways, it would start and run fine if I left it overnight. However, if I let it sit for over 1 day, it would be dead again. I figured the battery had done itself in from being drained completely so many times, so I got an optima red top. Put the red top in, and now still, if it sits a couple days, it is completely dead :sad: I am not sure if it is the same circuit or a different one that is causing a slow leak, but something for sure is draining my battery. The blower motor does not come on now at all with the fuse out, so I know it could not be killing it, but could the circuit still be draining the battery even though the blower is not coming on? :confused: What is the best way to diagnose this? Any advise would be greatly appreciated. TIA :seeya

 

That is a very wierd problem, have you added any electronics to the car at all?

I had a problem with my new battery going dead if the car sat for about a week, and suspected it was my window vallet, or my video system. I haven't let the car sit that long yet this year, so I don't know if the recent change I made to the video wiring fixed it.

I would start by disconnecting any electronics you added, if any at all.

Try disconnecting the climate control unit, and putting the fuse back in.

I don't know a lot about the hvac system, but I would expect the head unit controls the blower motor. There might also be a relay, it is possible that if there is a relay for the motor, it is just the relay acting up.

Hopefully someone else will have more in depth knowlege of the HVAC, but one thing that makes the Corvette unique is all the communication outside of the system.

Have you checked your DIC codes yet?

 

First off, make sure your hvac drain isn't clogged, check you BCM and blower motor for water damage. You really need a scanner that allows you to monitor the status of the control modules, it sounds like you have a BCM or HVAC controller staying awake. Let your car sit for about an hour with the doors open and you can feel all the relays, if you find a warm or hot relay you may have a sticking relay.

 

No, I have not added anything electrically at all. All stock parts. No sterio or anything else for that matter. I have replaced my HVAC unit with one out of an 02 since my stock one had ceased to light up on the display panel at all. However, the unit is not making the blower motor go on and off. I know this for sure because with the fuse in, and the HVAC unit totally unplugged and out of the car, the blower motor still turns on after a few seconds of the car turning off...

Where is the hvac drain? For that matter WHAT is the HVAC drain :confused:
I will definately check it!

I will take out the blower motor completely, but how do I "inspect it" for water damage? How would I know if it had any water damage? What would I look for?

But say even if the HVAC drain is clogged, and the blower motor does have water damage, how could that drain my battery with the blower motor fuse out :confused: That just doesn't make since to me. I think there is something else wrong with it for it to still be draining my battery slowly. One problem at a time though. So I will check the drain if someone will tell me where it is :) Thanks guys :chevy

 

The HVAC drain is a small black hose on the pass side that drains the water from the evap case, when this cloggs it backs water up into the interior of the car and it goes into the BCM and blower motor. Just remove the kick panel and look for signs of water or dampness.If you got water into the blower it will usually apper rusty. The drain hose is on the firewall and a pain in the butt to see withjout a lift. My best GUESS would be a faulty body control module (big silver box in pass footwell) is causing your battery drain, one of its internall relays may be stuck on.

Do you own a multimeter???

 

Thanks for the info on the drain location. I'll check it out.

Yes, I do have a multimeter, a rather good one at that. And yes I know how to use it. Got any tips on what to check and look for to see if the body control module is bad? :confused: Thanks :cheers:

 

Do a parasitic draw test. Hook your meter between you batt and pos cable in the amperage setting(hook it up corectly or you will blow your meter fuse) after your car times out observe the miliamp scale and start pulling fuses and relays you will see a drop when you hit the one that is powers whatever causes the draw.

 

There was a GM TSB for people who complained about musty odors from the HVAC system. The dealer would install a blower fan afterrun relay module, which ran the blower for a few minutes after the car was shut down, to reduce the moisture build-up on the evaporator coil. Maybe your car this dealer modification, and it doesn't work correctly. (stays ON too long)


[Modified by ersatz928, 11:31 AM 5/3/2004]

 

:iagree: this is the best way to locate your problem. after you find the system that is causing your problem they you will have to work on that system piece by piece. i think there will also be some stuff that uses some power like the radio all the time but this should be very small.
good luck

 

Don't suppose you know where the location of this additional relay would have been installed :confused: Thanks for the info! :D

 

usually the afterblow module is near the blower motor, it would be a black box with 4 or 5 wires coming out of it. If you email me your VIN, I can get you a dealer history report and let you know if one has been installed.

 

Sent you an IM with my VIN. (Sorry- I don't know how to e-mail from this site) Thanks :seeya

 

Okay- I'm gonna throw a curve ball out there and hopefully someone can make sense of it. I sure can't! Yesterday I had charged my battery up and got it to operating voltage. drove it around and everything. After I turned it off, it would still start up no problem. So I disconnected the positive cable from the battery treminal. Came back to start it today after re-hooking the pos cable and it was completely dead. It read 3.X Volts across the battery posts. HOW IN THE WORLD could my battery have drained thru the negative cable with the positive side COMPLETELY un hooked??? :confused:

 

There is no load on the battery when it is un-hooked, no circuit is completed. I hate to say it, but the new battery is probably toast now too.

 

I've come to that conclusion too. Turns out the red top can't hold a charge for very long. It wasn't brand new... My brother used it in his formula for a while then took it out. It had been sitting for a while in the garage before I put it in the Vette. I'm going to go to sears probably sometime tomorrow and see if they will warranty it out for a new one. I put a good battery in it (the one from my T/A) and it held solid. So I'm hoping a new battery will be the end of this electrical fiasco.

...That is besides the blower motor not working properly...

Thanks for the help so far everyone :cheers:

 

Don't know if I have a related problem, but I had my battery go dead on my '04 with only 900 miles on it (had it for three months). Again, it would not hold a charge after driving it. Took it to dealer yesterday and they replaced it under warranty. I'm hoping I just had a weak battery from the factory since the service manager said that he has seen that with a lot of Suburbans. Car is stock electrically except for a Window Valet. I thought it might be doing something to the accessory power that I was not aware of...

 

04's went back to a top post battery, I haven't had one of those go dead in a new vette yet but we sell them quick so they don't sit on the showroom floor very long.

 

sent you an IM with you basic history, your car didn't spend a lot of time at the dealer, there were also 2 no problem found complaints.