Rewiring (easy) bypass for simple 911 heat?

[nesslar]

Ok, I've looked at the drawings and now I'd like to ask for confirmation of what I think will work to obtain heat without removing the engine compartment blower. I assume air will flow past that reaer blower if it is left in place. If not, then I'd yank it of course.
I have pursued this idea for use in case either or both the engine compartment controller and rear blower is/are shot. Please see below, the diagram on the left.
If I disconnect (at the engine compartment controller) wires 3,4,5,6,7, and 8 (even #10 as well), then connect wire 3 to wire 4, will the footwell blowers, assuming they are good, work? This would bypasse the rear blower and the EC controller and associated sensors. With those two items disabled as such, hot wire 3 connected to 4 will supply 12v. to the footwell blowers when the console auto-switch is put to use. Right? Also please refer to the diagram on the right. It shows the power source for the footwells, wires 3 and 4. They come to life after the small relay jumps into action, which is activated by that Reed switch. My plan takes all that stuff out of the equation, of course.
For simple daily driving, it strikes me that all the controllers and sensors are irrelevant. Why not go with such a means of just switching on heat or not?
Assuming also that the console switch and its associated wiring are good, this looks right to me.

[aj88cab]

You don't indicate if you have manual or auto heat. But if I understand what you are planning to do, I believe your footwell blowers will run all the time. For the manual system the "0" position on the dial between the seats is not "OFF", it is the same speed as position "1".

See this thread for more info:

Help! Does anyone understand the footwell blower circuit?

[nesslar]

'86 with factory auto-heat.

[aj88cab]

I am not certain if the "0" position on the AutoHeat systems works the same as on the manual systems (i.e., positon "0" & "1" the same). Others may be able to confirm. But if so, you will have the foot well blowers running continuosly.

Besides the "0" position issue, if you bypass all the control circuit as you described, you might disable the heater servo device. With that disabled there will be no way operate the heater "flapper" boxes so there will be no way to redirect the heat into the car. I am guessing to some degree on this issue since I have no real experience with autoheat.

It sounds like your blazing new territory with modifications to the autoheat system

Good luck!

Edit - In thinking about it, since the dial between the seats is the only way to control the heat (no levers here) you might be on to something for the autoheat crowd. It makes sense that "0" is really "OFF" with the autoheat. But there's still that servo issue. Now you just have me thinking out load and that's dangerous

[nesslar]

Appreciate your responses. I'm studying my new Bentley Manual for the appropriate year's wiring relative to heat. I am intent upon learning enough to be of danger to myself before actually diving "in there".
Actually I don't see anything that is scaring me off as yet. BTW, the Bentley looks like quite the book.

[Rot 911]

I think you are looking for a solution to a problem that doesn't exist. I have heard of lots of engine compartment blower motors going bad, but not a single instance of the engine compartment controller going bad.