Twood

I am attempting to fit a Cup bypass pipe as per the article by Bill Gregory. It suggests using a 51 ohm 15 watt wire wound resistor and a 18K ohm 2 watt resistor to fool the system into thinking the blower motor is still there.
http://tech.rennlist.com/911/pdf/add...ipeInstall.pdf
The problem I am having is my local electronics store in Brisbane Australia do not have these exact resistors.
My question is - are there alternatives that I can use?
I am coming from a point of total ignorance in this area so if you can help please explain in a way that I can go to the electronics store and ask in the simpliest terms.
Thanks for any help.

jneteler

What do they have that is close to the specification?

I'm sure of the electrical magicians here can guide with alittle extra info.

Regards,

JNeteler

PORKERINO

If the job can wait until August, I'll bring you the resistors myself as arriving in Brissy, alternatively connect different values in series/parallel depending on what you have available, or in the case of resistors, go for a slightly higher value! Do the calculation first
Porkerino

jgrosjean

I don't think the exact value matters very much. The blower is only a few ohms.
I used two 82 Ohm 5W resistors in parallel (41 Ohms) because I had them in a box or resistors. 51 Ohms is not very common anyway. You can probably find 100 Ohms and put them in parallel.

Twood

In the article it says to use a 51 ohm 15 watt wire wound resistor for the blower motor and and a 18K ohm 2 watt resistor for the temperature sensor.

My electronics store suggested and supplied 2 x 100 ohm 10watt resistors and 4 x 18K ohm 1 watt resistors. Does this sound right.
The HVAC system is acting like when I had the rear blower motor disconnected prior to replacing it.

Does any of this make any sense ?

Rocket Rob

Yes, that should be good for the large resister.

Two 100 ohm 10 watt resisters in parallel is equivalent to 50 ohms and 20 watts.

The second set you would have to install the 4 resisters in a certain way.

Two pairs of parallel resisters put in series. This of it this way, 2 x 18ohms + 2 x 18 ohms = 9 ohms + 9 ohms = 18 ohms.

I hope this helps

darth

It may be important that the 51 ohm resistor is of the "wire wound type" (i.e. as the article describes) as opposed to ceramic to mimic the inductance characteristic of the motor's wire windings?

Hope this helps
Bill
90C2

Twood

I asked for wire wound resistors and they look like the one in the picture from the write up. In saying that they also look like a ceramic block.
I had the resistor set up tested and the 51 ohm 15 watt wire wound resistor tested at 48 ohm and the 18K ohm 2 watt resistor tested at 18.2K.
I used the scantool to delete all the error codes but still the bypass setup still acts like there is a faulty or no blower motor installed.
I am sure the answer is very simple and I am just doing something dumb.
Thanks for the suggestions so far.

Gus

If I recall correctly - someone on here said that the fix you are working on will not work on earlier models I tried it with my 91 and had no luck - PRobably will take a smarter than I am computer geek to figure out what is really needed - trick is in fooling the heat vent (by rear wheels) servos so they open or close to provide heat to the cockpit area

mpeters951

I've just done this mod in my '90 C2 w/o any problem or issue whatsoever. All HVAC functions behaving perfectly. Plenty of air volume/flow inside, either heat or A/C, no problem.

I'd read the write-ups carefully and found the required pieces here for a few dimes:

http://www.rselectronics.com/content/retail.aspx

The larger resistor I used was not an exact match of spec as in pic, the smaller was.

Hope that helps.

Gus

Maybe I have it backwards - The issue is not with the earlier models but maybe the later 91+ that the change won't work to fool the HVAC computer - I know I can't get my heat to work at all - - but if I pull the flaps open mechanically - I get more hot air than I want -.