: Do I have a bad Blower Motor Control or Blower Moter ????



05lover
07-26-10, 10:08 PM
2005 STS

So that last week my blower for my HVAC has been going in and out till yesterday it finally went out. All fuses and relays are working fine. So I removed the glove box and did some investigation. I noticed that the wire harness plug that is located next to the dash passenger side panal is extremly hot. I disconected it and noticed that the ground plug is a bit burnt. I turned on the car and turned on the blower and it seemed to work. But again the harness and ground wires got extremly hot. I've also noticed this problem occures when the blower is on only. I tested my blower motor and its pulling (constant 12v@0.8amps varible speed at 1-7v@0.1-0.5amps) then I tested my blower motor controller and all wires seem to be giving off the right voltage but notices that the ground wire was giving a reading of 1v when that fan was on high. I just wanted to know if the BMC is the problem and needs to be replaced at $155 or maybe my BM is going bad or maybe my ground wire is bad.

Thanks guys

next2pool
07-26-10, 11:13 PM
2005 STS

So that last week my blower for my HVAC has been going in and out till yesterday it finally went out. All fuses and relays are working fine. So I removed the glove box and did some investigation. I noticed that the wire harness plug that is located next to the dash passenger side panal is extremly hot. I disconected it and noticed that the ground plug is a bit burnt. I turned on the car and turned on the blower and it seemed to work. But again the harness and ground wires got extremly hot. I've also noticed this problem occures when the blower is on only. I tested my blower motor and its pulling (constant 12v@0.8amps varible speed at 1-7v@0.1-0.5amps) then I tested my blower motor controller and all wires seem to be giving off the right voltage but notices that the ground wire was giving a reading of 1v when that fan was on high. I just wanted to know if the BMC is the problem and needs to be replaced at $155 or maybe my BM is going bad or maybe my ground wire is bad.

Thanks guys

That's usually an indication of a poor connection. The resistance causes the wire and connector to get hot and many times will burn the connector right off. I would look at the connector very closely and if possible scrape or clean the terminals as best as possible. Blower motors for some reason seem to be especially vulnerable.

05lover
07-27-10, 06:02 AM
Update:

When the blower is off I get great continuity between the ground on the resistor and the body. When the blower is on high I get a no continuity reading could it be possible that my ground wire leading to the resistor is bad?? The action of the blower to be on is causing all this to happen and its only the ground wire on the harness next to the dash panal. weird thing is the blower controller module dosnt even connect to that harness it connects to another harness that goes threw the firewall.

Blower motor:
High speed 1v reading
Low speed 7v reading

Blower motor controller:
high speed (ground 1v, controller wire 4v, constant 12v, variable motor 1v)
low speed(ground 0v, controller wire 4v, constant 12v, variable motor 7v)

alexillac
07-27-10, 06:54 AM
Sorry that I cannot give you any advice on your Blower-Motor-Issue, but you wrote that you removed the glove box. How did you do that? Would be grateful for a description so I can lubricate away my climate-noise-prob.
thanks
alex

ewill3rd
07-27-10, 09:10 AM
Your testing methodology or the way you are translating it is confusing me.
Are you doing voltage drop testing or resistance checking?

If you have a burnt up connection my advice would be to replace both items that are connecting.
Often the blower motor will have a bad armature or something inside that will cause an overcurrent condition which can cause overheating, arcing, and a worsening condition.
Replacing one or the other will just foster a new issue with the part you put in.
Again this all depends on what you are actually seeing in the car.
Pictures would be fabulous.
Clarification on your testing methods would be good, but not really required.

next2pool
07-27-10, 01:01 PM
Update:

When the blower is off I get great continuity between the ground on the resistor and the body. When the blower is on high I get a no continuity reading could it be possible that my ground wire leading to the resistor is bad?? The action of the blower to be on is causing all this to happen and its only the ground wire on the harness next to the dash panal. weird thing is the blower controller module dosnt even connect to that harness it connects to another harness that goes threw the firewall.

Blower motor:
High speed 1v reading
Low speed 7v reading

Blower motor controller:
high speed (ground 1v, controller wire 4v, constant 12v, variable motor 1v)
low speed(ground 0v, controller wire 4v, constant 12v, variable motor 7v)

It could be high resistance on the ground side. The reason the controller isn't connected to the blower motor per se, is because it sends a low current signal to another module which then controls the motor--not like the old days :)

05lover
07-27-10, 01:53 PM
Sorry that I cannot give you any advice on your Blower-Motor-Issue, but you wrote that you removed the glove box. How did you do that? Would be grateful for a description so I can lubricate away my climate-noise-prob.
thanks
alex

There are 5 screws in total to remove the glove box. Three screws are on located in the box towards the top lip 1 on either side and 1 next to lock very hard to see so use a good flash light. the other 2 are at the bottom of the glove box.

05lover
07-27-10, 06:41 PM
Sorry I'll try to clairify this.
My problem is my blower will not shoot out an air from my vents what so every and all fuses and relays are working fine. So I removed my glove box and found that once I wiggled the wireharness around the blower came back. Then I noticed when the blower is on (expecially on high speed) the wire harness that is at the passenger side right there when you open the dashside panal is extremley hot. This harness (harness 1) has a plug while there is also another harness (harness 2) but no plug just wires both going to the engine cabin. So after wiggling the wire everything works fine except the fact the wire harness1 would get hot so I opened up the plug and noticed that the black ground wire pin is melting the plastic and that was the only wire of the whole harness that was even getting hot. I also noticed the hot ground problem was only occuring when the blower was turned on from the hvac control unit. So I ran 3 tests (blower on hi/low & blower off) with 2 conditions (resistance & voltage) on the ground on harness 1 the blower control module, the blower. And below are the results

CAR ON
Blower set off:
BCM:
black wire: (resistance to body ground=0 resistance to ground on harness1=0 Voltage w/body ground=0v)
Blk/gry: (voltage w/body ground=0v)
Lt-blu: (reistance to Lt-blu on blower motor=0 Voltage w/body ground=0v)
Purp: (reisitance to Purp on blower motor=0 Voltage w/body ground =0v)

Blower motor:
Lt-blu: (resistance to purp on blower motor =0 Voltage w/BG=0v)
Purp: (Voltage w/BG=0v)

Ground on harness 1:
Black: (resistance to body=0 Voltage w/BG=0v)

Blower set on low speed
BCM:
black wire: (resistance to body ground=0 resistance to ground on harness1=0 Voltage w/body ground=0v)
Blk/gry: (voltage w/body ground=4v voltage w/harness1 ground=4v voltage w/BCM ground 3v)
Lt-blu: (reistance to Lt-blu on blower motor=0 Voltage w/body ground&harness1&BCMground=all 13v)
Purp: (reisitance to Purp on blower motor=0 Voltage w/body ground&harness1= 9v voltage w/BCM ground = 8v)

Blower motor:
Lt-blu: (resistance to purp on blower motor = 0 Voltage w/BG & harness 1 & BCM=13v)
Purp: (Voltage w/BG & harness 1 & BCM=9v)

Ground on harness 1:
Black: (R to body= 0 Voltage w/BG=0)


Blower set on high speed
BCM:
black wire: (resistance to body ground=0 resistance to ground on harness1=0 Voltage w/body ground=1v voltage w/harness1=0v)
Blk/gry: (voltage w/BG&BCM&harness1=0v)
Lt-blu: (reistance to Lt-blu on blower motor=0 Voltage w/body ground=13v voltage w/BCM&harness1=12v)
Purp: (reisitance to Purp on blower motor=0 Voltage w/BG&BCM&harness1=12v)

Blower motor:
Lt-blu: (resistance to purp on blower motor = 0 Voltage w/BG&BCM&harness1=12v)
Purp: (Voltage w/BG=1v voltage on harness 1&BCM=0v)

Ground on harness 1:
Black: (R to body=0 Voltage w/BG=1v Voltage w/BCM=0v)

I can say from my limited knowledge that its 1 of 3 things the wire harness has a bad ground or a short somewhere, the BM is going bad(after all the test I think it's just fine), or the BCM is bad allowing power to leak into the ground.

05lover
07-30-10, 06:33 AM
Swapped the blower motor and resistor with a friends STS and still same problem wired harness is over heating..maybe this is a bad ground issue...I will try and spend the weekend on doing more investigative work...also the harness dosn't heat up when the fan is on speed 1 or 2

ewill3rd
07-30-10, 09:02 AM
Don't be fooled by the mere presence of heat.
Current flow produces heat.
I have almost burned my hand on some relays on a few cars and they are just operating as they should.

I'm not saying that you don't have a problem, but don't assume you do just because something is warm to the touch.

05lover
07-30-10, 04:31 PM
I agree with current flow producing heat but this harness is getting so hot it burns ur finger. The 1 wire which is the ground on this harness is getting so hot it's melting the plastic of the harness. I can only think of 1 issue to cause this and it's a bad ground on the harness. Since this is a car I can just tap both harnesses to the body and this will make up if the ground is bad some where down the line

ewill3rd
07-30-10, 09:55 PM
Actually a bad ground in this case would likely cause non-operation of the blower, or possibly excessive heat at the ground connection itself.
The conductor should only get too hot if it is flowing too much current.
That would indicate that the blower is drawing too many amps for the conductor to handle which couldn't happen with a faulty ground.

It sounds more like the blower motor has some sort of internal issue to me.
I don't see how you could swap the blower and resistor from another car and still have the same problem.

However, if you want to check the ground to be sure, the blower control module provides the motor ground and it is G201 which is located behind the right side kick panel.
With the sill plate/kick panel removed you can't miss it.
It is a large wire bolted in about halfway up the lower portion of the pillar.

05lover
08-06-10, 04:50 PM
Well I know now its a bad ground issue because the blower motor is pulling under 1amp. So I went to harness1 took the ground wire that is getting hot soddered in a new wire and reattached it to the body ground and vola my problem is fixed. I figured since this is car electrical and not home I can use any ground on the body just making sure the wire is equal or smaller gauge. I was going to do the same to the resistor ground but I didn't have to this seemed to make everything work right. Thanks to everyone who chimed in!!

ewill3rd
08-06-10, 09:56 PM
It would be cool if you could find the problem, but I am glad to hear you bypassed it and got it working.

BrandonW
08-07-10, 03:29 AM
glad to know that you finally managed to fix the issue