Fresh air blower not fully working

suckho · 01-09-2016, 03:59 AM

My car is 1982 911 SC (RoW model, no AC). Fresh air blower is not working on I, but works on II and III. What could possibly be wrong?

I have been looking this electrical diagram:
http://www.pelicanparts.com/911/911_parts/Electrical/911_electrical_82SC_Part4-1.jpg

Is it possible to access/change those resistors in fresh air blower or must I change the whole unit? Where can I find the blower and what is the easiest way to access it?

How about the dash switch? Any way to easilly access it?

cary · 04:45 AM

Dash switch needs freshening up. Old school copper contacts need to be cleaned. On a 914 it's held in with one 10mm nut up on the firewall. IIRC it's the same.
Be careful it's a tight squeeze coming out. I'd do a 3m tape job around the dash to protect from scratching before you start. Be careful with the light bulb wires as you pull it out. Oh yeah disconnect the battery before you start, lots of live key off wires around there.

That switch sends the ground signal to the blower. Before you start hit up Amazon for some Deoxit.

suckho · 01-10-2016, 09:48 PM

Is it unlikely that the problem is elsewhere, like in connections, resistors or the blower itself? If the problem was in this sliding switch contact, shouldn't it work somehow at some position and then get worse over time..? Now it just stopped working so I suspect it could be burnt resistor or something else. It doesn't look very easy to pull out the panel from the dash..

cary · 01-11-2016, 07:22 AM

You are correct. Not Easy. And yes it should work some of the time.
Back to the blower motor. Removing it isn't as easy as it looks. The two 6mm mounting bolts are very hard to get restarted when you go to reinstall it.

914World.com - The fastest growing online 914 community!
Look at Page 121-123. I never did post a picture of the resistor. I'll see if I logged it in to my jpg file.

suckho · 01-11-2016, 09:17 PM

I think this is exactly what I was looking for:

Removing the Heating & Ventilation (HV) Control Levers

Removing the Fresh Air Fan assembly

Thanks frankc!

suckho · 01-15-2016, 12:06 AM

I did some debugging with multimeter and verified that dash switch works correctly. This is good because it would have been really PITA to remove/fix.

Then I removed and disassembled the blower motor and found out that one of the motor resistors is kaputt. It is loose from other end and doesn't have any contact.

Does anyone know if these resistors are available anymore? I didn't find any similar part..

I guess my options are then to get second hand replacement part, fix the broken part, or get some replacement that is not 100% the same.

I have been told that soldering this loose connector is not a good idea. I'm now thinking if I could drill a small hole,guide the connector through it, and bend on the other side..

Any ideas?

javadog · 01-15-2016, 03:49 AM

Can you not fix it by putting the wire back where it was?

JR

john walker's workshop · 01-15-2016, 04:08 AM

That bolt that holds the assembly to the firewall completes the ground, which is the function of the switch. I've fixed a lot of "dead" blowers simply by tightening that bolt better. Being that two speeds do work, it's probably not a ground issue, but just wanted to throw that in.

cary · 01-15-2016, 06:36 AM

I think have about 5 of them disassembled. But I'm half way around the world.
Great picture by the way.
If you end up needing my help. Shoot a couple close ups of all the embossed numbers.

suckho · 12:18 AM

Fixed!

I drilled two holes: one above and one below the original fixing. Then I took one loop from resistor coil to make wire a little bit longer and guided it in through the upper hole and back out through the lower hole. Tested it already in car and seems to work perfectly. All parts are now cleaned as well so I just need to put them back together now.

Let's see how it lasts.. Hopefully the next 20 years

suckho · 01-16-2016, 01:13 AM

Quote:

Originally Posted by javadog

Can you not fix it by putting the wire back where it was?

No. The original connector was pressed very tight and I just couldn't force it open again.. Not much space there and so it is difficult to apply force without breaking anything. I hope my alternative fix keeps it connected for years to come

guli · guli's Garage

While you're in there do clean the contacts on the bi-metal strips under the resistors and make sure there is a gap. My fan always ran at full speed as soon as it was turned on due to corrosion and the contacts being stuck closed. The function is that when the resistors get too hot the fan should go full speed until they are cooled down so that the contacts open again. This is why the resistors are in the air stream.

suckho · 11:42 PM

Yes, and you can actually test function of those bi-metal strips by heating them with hair dryer