gregmitch

My 964 came with a Fabspeed carbon fiber heater bypass pipe and I'm going to put back the stock heater blower motor so I can have maximum heat and defrost this winter. (C4 snow fun!) Currently my fan speeds do work but defroster goes on for a few seconds and then shuts off...The question I have is what, if any, jumper wires or relays I should be looking for to remove to put back to the stock setup. I've read about possible jumper wires when installing the bypass but I couldn't figure out a definitive answer.

Once heater blower is back in, bypass pipe will be for sale

Porsche917K

Look in the fuse box on the left side of the engine compartment. You will probably see one of the relays is missing and some jumper wires in it's place.

-nick

I have mine set using +12v from the ac relay into the signal wire for the ccu through the blower motor relay (purple wire jumper). Also a '91 C4. No problems with any of the ccu or defrost functions and there is always more than enough heat available for snowy fun

gregmitch

Your defrost works well if the car is sitting? That's my biggest concern is when the car isn't moving.
I'll open up my fuse panel and see what jumper wires are there.

-nick

Indeed! The ac compressor clicks on, fan speed goes to 100%, and all of the air is diverted to the windshield and side vents. The fan speed does vary, I think that it won't reach 100% until the heat exchangers have warmed the air.

Foxman

See this thread here.definitive bypass thread If you want to return the blower motor, happy to take it back.

gregmitch

Jim I really do appreciate that offer (and this is why RL members are the best) but I'm going to keep it in case I have any issues this winter.

Revvin_911