'Fresh Air Blower Fan' stopped working

[webrest]

Hi All,
Fresh Air Blower fan has stopped working.

Vehicle '85 911 3.2

I have attached the wiring diagram with important points of interest marked on the image.

My questions are .
1/How do I check that the fan motor is actually working as a stand alone item?
2/What does the symbol mean that is incorporated in the blower motor wiring diagram? [It is marked on the attached image]
Looking forward to some info on this.
Regards
Dave

[kerthunk]

The circle with the M in it is the motor itself. To test it, you just need to put 12v through the motor. Looks like you can use pins 3 + 4 on the blower. The diagram is a little too small for me to read.

[webrest]

Originally Posted by kerthunk

The circle with the M in it is the motor itself. To test it, you just need to put 12v through the motor. Looks like you can use pins 3 + 4 on the blower. The diagram is a little too small for me to read.

Thanks John,
Sorry the diagram didn't reproduce well. It started off my end a very clear image it must be the resizing when placed on the forum.

Duh! of course the little symbol would mean the motor. Sometimes I wonder if I am actually awake.

I gather from what you are saying that I should put +12v to terminal #4 and run a wire from terminal #3 to ground [-]

If the motor does not run is it conclusive that it has issues and needs to be removed for further investigation.

R.
Dave

[theiceman]

yup ...
actually you are lucky .. these usually smoke and catch fire

[kerthunk]

Originally Posted by webrest

Thanks John,
Sorry the diagram didn't reproduce well. It started off my end a very clear image it must be the resizing when placed on the forum.

Duh! of course the little symbol would mean the motor. Sometimes I wonder if I am actually awake.

I gather from what you are saying that I should put +12v to terminal #4 and run a wire from terminal #3 to ground [-]

If the motor does not run is it conclusive that it has issues and needs to be removed for further investigation.

R.
Dave

Yup, +12v to #4 and - to #3. Be sure that the +12v you use for this test has a fuse in it (maybe 5 amp or so). If the motor is shorted out, you don't want to set it on fire!

[Decolliber]

I added fuses to both the fresh air blower and the front condenser fan, as they are both potential fire hazards.

[crownarch]

If your blower does not operate with 12vdc applied directly to it then you more than likely have a bad controller. Search for "backdating blower" on this forum, go to page 2 and then find the post "Carrera - Removing Engine Compartment Heater Blower". I just went through this whole scenario and there were some ingenious individuals that figured this thing out as you will see on the post above. If your brain starts to cook when reading the above post, let me know and I will try to help you out.

[theiceman]

Originally Posted by crownarch

If your blower does not operate with 12vdc applied directly to it then you more than likely have a bad controller. Search for "backdating blower" on this forum, go to page 2 and then find the post "Carrera - Removing Engine Compartment Heater Blower". I just went through this whole scenario and there were some ingenious individuals that figured this thing out as you will see on the post above. If your brain starts to cook when reading the above post, let me know and I will try to help you out.

are you sure ? i would think if your blower does not work with 12v applied directly to it ( connections 3 and 4 ) , you have a bad blower ... just sayin ....

[crownarch]

Iceman - you are correct as I made an incorrect statement. If you have voltage to blower and it does not activate then the blower motor is more than likely bad. Sorry for my error but, fingers were typing faster than the brain was operating. You can also find a post on the forum of where and how to obtain a new blower motor. If you need that post let me know and I will go through my records and try to find it for you.

[Elombard]

wait I thought the fresh air blower was in the frunk? Is there a cheapy way to fix this motor? mine is out too.

[kerthunk]

Yes, the fresh air blower is the one in the frunk. It may be possible to fix, all depends on what is wrong with it. The motor is available from a few different places (use google). It is pretty easy to swap out. Pelican has the motor as well, but it comes with more of the assembly and therefore runs $200. The motor alone can be had for under $100.

[Elombard]

Thanks John - will investigate.

[Algernon]

I has same problem, and thought I could save $100 by just buying the motor. But there is no set screw or flat on motor shaft to allow easy removal of the fan cage. So I ended up getting full assembly for the extra $100, but probably saved more than that in avoiding hassle.

[Jerome74911S]

Originally Posted by crownarch

If your blower does not operate with 12vdc applied directly to it then you more than likely have a bad controller. . .

So, if my blower works intermittently, or does not want to work on its various speeds all the time, then it might be the controller?

Sorry for hijack.

[kerthunk]

Originally Posted by Jerome74911S

So, if my blower works intermittently, or does not want to work on its various speeds all the time, then it might be the controller?

Sorry for hijack.

If your blower is only working intermittently, I would take a look at the contacts behind the dash. The contacts that deal with the fan speeds are at the right side on the first pic and the bottom on the 2nd pic. The 3 pads with the wires attached are for the 3 speeds. The larger pad is the +12v. When you slide the lever over, it simply bridges the pads with the little arms attached to the lever.




Make sure that your contacts are clean and that the arms are making good contact with the pads. You can bend the arms a little if needed. Sometimes you need to bend the arms to the side to make sure that they are hitting "fresh" copper on the pads.

[Jerome74911S]

^^^ that's really quite interesting. It does seem as if you could select two speeds at once. What happens then? Damage?

[kerthunk]

The bottoms of the little arms are ball shaped, so it would be hard to select 2 speeds since there is the gap between the pads. If it somehow did touch 2 pads at the same time, the electricity would follow the path of least resistance and pick the faster speed. No damage would occur.

[Jerome74911S]

Thank you. I'll dig in there to make sure that the wiring connections are up to snuff.

[webrest]

Thank you John for the advice and the control photos, I can understand very clearly now how the system works.
Having tested the blower individually it is clearly not working..
I was only ever getting one speed anyway so I might pull the switch after I have looked at the blower itself and see what is going on there as well.
Thanks to all that showed interest
Regards
Dave
Dave

[Elombard]

Has anyone tried taking these mtors to a place that 're-winds' electric motors? Probably cost more than a replacement.