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blower not getting enough amps?? 1998 318i

 
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kleve



Joined: 07 Jan 2002
Posts: 19
Location: Cleveland, Ohio USA

PostPosted: Fri Oct 01, 2010 5:08 pm    Post subject: blower not getting enough amps?? 1998 318i Reply with quote

When I crank up the heat on the digital display, I don't hear the fan or feel air from the vents. Got at the blower, figuring it was dirty contacts. Cleaned them, but no joy. Connected 12VDC directly to blower motor and it ran great. Put a meter on the wires going to the blower and, with ignition on, they show 8 volts when interior display is set to highest fan speed and 10 volts when I poke it down to the lowest. Since the blower motor works fine, and since I'm getting voltage to the blower, I'm guessing I've got a dirty connection upstream which is reducing the amperage. Bentley says the blower sucks 13 amps max. I've got 3 volt/ammeters and they all max at 10 amps. Before I go out and buy another ammeter, is there an obvious something to look at for a problem like this? Also, I don't know where these two wires go (a green/yellow and a brown/yellow), so I don't know where to find all the other contacts to clean.

Might be relevant: The radio/CD player seems to have power supply problems too.

Thanks much.
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jdob28



Joined: 10 Aug 2003
Posts: 178
Location: Newnan, GA USA

PostPosted: Sat Oct 02, 2010 7:39 am    Post subject: Reply with quote

I would look at the resistor pack. I'm not sure where it is located on your car but it will be located somewhere in the ducting to keep it cool. Have you looked at the wiring diagram and checked all the connections for corrosion?
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94 325IC (sold)/ 98 328IC (sold) / 98 318TI (sold)/ 99 M3 (e36)
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PJK



Joined: 14 Feb 2002
Posts: 1829
Location: Shingle Springs, CA

PostPosted: Sat Oct 02, 2010 5:49 pm    Post subject: Re: blower not getting enough amps?? 1998 318i Reply with quote

We need a bit more information here. Where were you connecting the voltmeter? If you measure 8 volts across the blower it should be running.
What year is the car? The early e36s use a resistor pack to control blower speed. The later cars with the digital have in place of the resistor pack what they call a final stage. Those have proven to be troublesome.

Phil

kleve wrote:
When I crank up the heat on the digital display, I don't hear the fan or feel air from the vents. Got at the blower, figuring it was dirty contacts. Cleaned them, but no joy. Connected 12VDC directly to blower motor and it ran great. Put a meter on the wires going to the blower and, with ignition on, they show 8 volts when interior display is set to highest fan speed and 10 volts when I poke it down to the lowest. Since the blower motor works fine, and since I'm getting voltage to the blower, I'm guessing I've got a dirty connection upstream which is reducing the amperage. Bentley says the blower sucks 13 amps max. I've got 3 volt/ammeters and they all max at 10 amps. Before I go out and buy another ammeter, is there an obvious something to look at for a problem like this? Also, I don't know where these two wires go (a green/yellow and a brown/yellow), so I don't know where to find all the other contacts to clean.

Might be relevant: The radio/CD player seems to have power supply problems too.

Thanks much.
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kleve



Joined: 07 Jan 2002
Posts: 19
Location: Cleveland, Ohio USA

PostPosted: Sun Oct 03, 2010 8:54 am    Post subject: blower not getting enough amps?? 1998 318i Reply with quote

jdob28 wrote:
I would look at the resistor pack. I'm not sure where it is located on your car but it will be located somewhere in the ducting to keep it cool. Have you looked at the wiring diagram and checked all the connections for corrosion?


Yes, cleaning all the connections is exactly what I think is needed. (Of course I'm open to more experienced opinions.) And, yes, I did check the wiring diagram in the Bentley's. Both wires to the blower come from the "final stage". But the manual doesn't tell me where this is and I can't see where the two wires feeding the blower lead to.

Also, it's possible that there are non-documented connections between the blower and the final stage. I'd like to clean those also (if there are any).

So, where is the final stage located and how do I get at it? And are there any connections between the blower and the final stage?

Thanks much for the help.
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PJK



Joined: 14 Feb 2002
Posts: 1829
Location: Shingle Springs, CA

PostPosted: Sun Oct 03, 2010 12:56 pm    Post subject: Re: blower not getting enough amps?? 1998 318i Reply with quote

I have the older car with the resistor pack but I think the final stage is where the resistor was in the older cars. Bentley doesen't show it very well but it is on the driver's side through the wall of the HVAC case. If there are interconnects between the final stage and blower which came from BMW they should be noted in the Bentley schematic. Bentley isn't any good about putting signal names on the wires but I think they get the connections fairly correct.

Phil

kleve wrote:
jdob28 wrote:
I would look at the resistor pack. I'm not sure where it is located on your car but it will be located somewhere in the ducting to keep it cool. Have you looked at the wiring diagram and checked all the connections for corrosion?


Yes, cleaning all the connections is exactly what I think is needed. (Of course I'm open to more experienced opinions.) And, yes, I did check the wiring diagram in the Bentley's. Both wires to the blower come from the "final stage". But the manual doesn't tell me where this is and I can't see where the two wires feeding the blower lead to.

Also, it's possible that there are non-documented connections between the blower and the final stage. I'd like to clean those also (if there are any).

So, where is the final stage located and how do I get at it? And are there any connections between the blower and the final stage?

Thanks much for the help.
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kleve



Joined: 07 Jan 2002
Posts: 19
Location: Cleveland, Ohio USA

PostPosted: Sun Oct 03, 2010 1:04 pm    Post subject: Re: blower not getting enough amps?? 1998 318i Reply with quote

PJK wrote:
I have the older car with the resistor pack but I think the final stage is where the resistor was in the older cars. Bentley doesen't show it very well but it is on the driver's side through the wall of the HVAC case. If there are interconnects between the final stage and blower which came from BMW they should be noted in the Bentley schematic. Bentley isn't any good about putting signal names on the wires but I think they get the connections fairly correct.

Phil



Thanks, Phil. Just looked at Bentley about getting at the resistor (where I need to go for the final stage)... i.e., the lower dash trim panel on the driver's side. But what does the final stage unit look like? How big is it? I have no idea what I'll be looking for.

Thanks.
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PJK



Joined: 14 Feb 2002
Posts: 1829
Location: Shingle Springs, CA

PostPosted: Sun Oct 03, 2010 6:57 pm    Post subject: Re: blower not getting enough amps?? 1998 318i Reply with quote

I have neve seen an e36 final stage but a friend with an e46 had one fail. I would say it is slightly larger than the resistor pack. It is made of aluminum with a connector on it. I has fins but you won't see them untill you remove the assembly.

I suggest that you push straght pins through the green/yellow wire and the brown/yellow wire and connect your voltmeter between them. Those are the leads to the blower. With the blower turned on you should measure a voltage between those leads which varies with the blower speed. If you can get more than 6 Volts between those leads and the blower is not running and since you have established that the blower is OK, there is a connection failure between that spot and the blower. If there is no Voltage move your pins and meter to the brown and blue/red wires. If you get a voltage there which varies with the blower speed setting and the final stage has no output is bad it is a good bet that the final stage is bad.

I just changed one on my wife's Mercedes Benz. They call it a blower regulator.

Phil

kleve wrote:
PJK wrote:
I have the older car with the resistor pack but I think the final stage is where the resistor was in the older cars. Bentley doesen't show it very well but it is on the driver's side through the wall of the HVAC case. If there are interconnects between the final stage and blower which came from BMW they should be noted in the Bentley schematic. Bentley isn't any good about putting signal names on the wires but I think they get the connections fairly correct.

Phil



Thanks, Phil. Just looked at Bentley about getting at the resistor (where I need to go for the final stage)... i.e., the lower dash trim panel on the driver's side. But what does the final stage unit look like? How big is it? I have no idea what I'll be looking for.

Thanks.
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kleve



Joined: 07 Jan 2002
Posts: 19
Location: Cleveland, Ohio USA

PostPosted: Sun Oct 17, 2010 6:35 pm    Post subject: Finding the Final Stage Unit Reply with quote

As it turned out, it wasn't too difficult to find the final stage... even though my Bentley doesn't mention it anywhere, except in the electrical schematic. On my '98 318i (American, left-side drive) I had to take out the lower dash trim under the steering wheel. Lying with my head on the floor close to the gas pedal facing up, I was able to see it towards the middle of the car, almost behind the center console. Actually, I memorized the colors of the five wires going to it and then looked for those five wires going to something.

To pull the plug (with those five wires) out, there are two tabs, one on the top, another on the bottom... you have to squeeze those together and then pull. It isn't easy to get a finger to the top tab though. It might help a bit first to push the plug in to loosen it, then squeeze the tabs and pull.

There are two screws to take out in order to remove the FSU. You'll need a short screwdriver with a six-pointed-star kind of tip. I can't believe I had one of these. The gods of Valkyrie must have been hanging around that afternoon.

Thanks for pointing me in the right direction.
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kleve



Joined: 07 Jan 2002
Posts: 19
Location: Cleveland, Ohio USA

PostPosted: Sun Oct 17, 2010 7:09 pm    Post subject: Three screws for dash trim... which goes where? Reply with quote

When I took out the lower dash trim on the left side (under the steering wheel), I carefully set the screws in the same pattern so I'd know which screw went in which hole. But then of course the screws got bumped together and now I don't know which screw goes in which hole. Anybody remember?

('98 318i, left-side drive)
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