vetteman741

98 coupe AT, dual digital climate control

OK so I have no blower fan when using my AC or heat.

I have no HVAC codes in DTC, I checked

I grounded out blower motor and it runs

I changed out BMCM with a supposed good used one

I have already searched all HVAC topics in forums

Now what, start ripping my dash apart to check wire continuity or buy a new BMCM for $150 and hope that is it (probably be weeks for me to afford that)

Is there any way I can test BMCM to know it is bad?

Why did I buy a late 90's GM when my others in the 90's gave me electrical problems too I just want to drive my car and enjoy it with some AC and defrost, It seems I can never win


I don't have enough hair left to pull it out

Yeah I am sure someone will say take it to the stealership, ha ha I can't afford that unless I get a second job

lucky131969

Do you have a service manual? Do you have a meter? Can you read schematics?

Bill Curlee

Have you checked all the fuses??

PEERPSI

So the positive was coming through the normal wire harness and you just provided a ground point? If so it would suggest to me that you need to look at splice pack 202 and ground point 202. Both the BMCM and the motor get there ground from that point. Both SP202 and G202 should be at the bottom of the A pillar just in front of the passenger door opening.

Bill Curlee

Well you would be wront to assume that just because the notor runs, the fuse is good.




Check ALL the fuses.

BC

PEERPSI

Hmm, Bill not trying to be a smarty pants but I come up with a different schematic for the 98.

Bill Curlee

You are absoluty correct,,, That was for a 01, Here is the one for the 98 FRONT mounted EBTCM car:

vetteman741

Yes I have a GM service manual (all 2000+ pages) didn't have a lot of time to search through it

Yes I have a multimeter

Yes I can (barely) read schematics

Yes I checked all fuses

I will have to check out ground point 202 and splice pack 202 when I get time.

Thanks for all the help, any more ideas let me know.

I guess if it was a ground, I will have a spare BMCM for when it does fry.

I hope I find this problem soon, I have to replace the ground point for my radiator fans too, they work half the time, and the other half the time I have to get under hood and move wires by that ground point to get fans to come on.

Thanks guys

lucky131969

Ok, you have the service manual, but you have not done the troubleshooting......?

"Under Diagnostic Information and Procedures"...there is a troubleshooting procedure for "Blower Motor Inoperative at Any Speed". That will isolate the issue. You have the bible....no need for guessing.....or parts changing.

vetteman741

Valid point, like I said I did not have a lot of time to go through the book. I must have missed that part of the book. Maybe I should have looked harder

Thanks for pointing out my stupidity

vetteman741

Followed the book diagnostics, only got to step 4 or 5.

Ground pack bad connection, wiggled ground pack, now it works so I will be going through the grounds this weekend.

Thanks for the help, I shoulda just looked at my book first.

and now I have a spare BMCM for if it ever goes out

AZ-vette

I'm having a similar issue, except my AC blower cuts out at higher fan speeds. It works fine at lower fan speeds. I'm thinking I have the same problem. However, I don't have the service manual to reference. Can you provide more specifics as to where to find the ground point 202? Thanks in advance!

Bill Curlee

G202

PEERPSI

If it works but cuts out at different speeds it can be control related rather then the ground. Need to know what year of car.

As I'm typing this I see Bill has beat me to the punch!

Bill Curlee

if you have automatic Duel Zone,,, heres what goes wrong with the controller:











If you have a manual system,, here what goes wrong:

AZ-vette

Thanks for all of the feedback and sorry for the slow response. I have a 2000 model year, manual transmission, with auto dual zone air controls.

The ground point seemed to make sense since I had the same issue last summer but only on the highest fan speed setting. A couple weeks ago I cranked the AC blower up and it cut out at both the highest and 2nd highest fan speed. So it seems to be progressing. I will check the ground point and report back what I find.

vetteman741

Anyone know which wire exactly in the Ground Pack is for the BMCM, I looked in my manual but I can't seem to find which wire it is, my ground problem is coming back occasionally. If I move the GP a little, the blower works fine for a day or two.

Bill Curlee

WHY,,,YES I DO!!

Here is your blower schematic. Loom at pin "F" in the connector.

REMENBER!! Each ground connector comes apart and there are male and female pins inside that cause issues:







CORROSION

vetteman741

Thank you Bill Curlee.

I did take it apart and cleaned it all up when I had it removed due to a little corrosion on the pins and ground recepticals, but I may have to add a bypass (additional) ground wire looped off Pin F wire if I keep having problems.

BTW did you say schematic was posted?

vetteman741

Anybody have a GM part number for these connectors if I wanna replace all mine that I have problems with, I would like to keep stock if possible, or if there is a better solution for new Ground packs.