ThomasC2

Finally I decided to build the bypass for the rear blower. Had a look on different ways of doing it here on the forum, but ended up with a design of my own. I haven't tried it yet (missing one small connector) but I'm really pleased with how it looks. The resistor for the engine is very small and shouldn't generate to much heat according to the store. And then I got the idea to use the whole sensor intead of using a another resistor. The sensor and the curled wire are mounted in the same pipe in the stock set up so I thought this would work to.

So I bought a box in aluminium, cut out some slots and vent holes. I will mount it on one of the bolt holes where the blower used to sit. On the black and red cables I put connectors instead of soldering them so I can take the box out of the car without cutting any cables. And this is the result:

Sire

Looks ,i'm curious if you can get the front blowers working.

stevepaa

What does this do for you?

ThomasC2

My objective is to get the front fans to run as the should. Everything is hooked up and I just have to reset the old error codes with my Scantool device, but now I can't get the probram to run properly on my new laptop

springer3

You know after the valve-adjusting screw driver there is expectation you will go into volume production. How much to build one for me? That is a great design, and I am by-passing the motorized rear blower.

Duck

What model year is your car? I still want someone to come up with a solution for early models (mine being a 90 model).

ThomasC2

My car is MY-92. I hope we'll fix the scantool problem during the weekend so I can report back if this works or not!

Ag02M5

Signing up.

mpeters951

As DUCK states above, I'm also very interested if there is any possible fix or workaround for the '90 MY cars. In my case, my interior fan speeds will only work when temp setting is on full blue. As soon as you move the temp setting up, blowers die.

I'm assuming DUCK has the same symptom pattern on his '90 as I do on mine. FWIW when I did the install last year I'd followed the resistor spec DIY precisely/carefully.

Duck

I have not tried adding the resistors, however I did a test with removing the connection to the fan and nothing worked. I do expect that the CCU is original and therefore I expect that the resistors will not solve the issue. We need an electrical engineer to figure this out for us.

Twood

Ditto

ThomasC2

Hi guys, I need some more help/info on this bypass issue!

I've now tried a setup with a 50 ohm resistor (1 Ohm less than the instruction says), 15 watt, and I almost get it to work.

I can run the front fans at any temp on speed 1 & 2, but when I turn up the speed to 3 & 4 the fans goes down in speed (or if one cuts out, hard to say) if I leave the blue dot. If I turn down the temp to blue again the fans goes back to the correct speed at 3&4 again.

So it looks like we're almost there. Is is so sensitive with the resistor, can really 1 ohm make a difference? Can I buy a, let's say 60 Ohm resistor intead to get som buffer if 51 is so close?

Any ideas?

Thanks

Thomas

dave-C2

I did the same thing successfully a few years ago with a 50 ohm resistor, so I don't think the CCU is that sensitive. It's critical, however, to clear the faults in the CCU - at least initially.

As I understand it, the CCU invariably will identify some faults that are spurious just because the CCU processor speed is out of synch with the balance of the car's controls - either the CCU is too quick or too slow.

Someone who knows better can correct me, but based on my shop's experience as well as my personal experience, it's save to say most 964 CCU faults are artificial.

BTW, take care it you ever remove the CCU unit, the wiring to the two harness plug can be accidentally loosened from the plug and cause faults. I was too heavy handed and the loose ground wires caused all sorts of problems.

ThomasC2

we have a laptop with the scantool hooked up so we clear the codes "all the time". I will try with some other resistors tomorrow.

MPB993

Hi there

Not sure if the 964 is the same ccu as the 993 but I removed and jumped the rear blower relay to provide the ccu with 12v at pin 19 after removing the rear engine blower. I also placed a 18kohm resister instead of the temperature sensor on my 993. No codes seen after doing this on scantool. I get heat and full front blowers. It might save some of you from constructing a box but I know it works on my 95 993 so if you have wiring diagrams it maybe worth investigating. On my 993 it was relay socket pin 30 and 87 connected after removing the relay.

BR, Mark.