I've adapted (or nearly adapted) my OEM AC dash controls to an AC delete heater box. I'm looking for the heater motor wiring diagram for the non AC application. There are a few things different and the drawing spells it out. Something like the one attached but for non AC .
I checked out Austin's Third Gen and few other sites but can't find what I'm looking for.



The difference in specific is the 4 wire resistor whereas the non AC has a three wire resistor. That and the colour code of the fan speed selector. Mine is 3 speed and this drawing represents a 4 speed.

 

Found it.
I'll post it here for posterity.



Three wire resistor non AC heater blower.

 

Most people just re-use the original "AC" wiring harness and VERY few convert the controller itself. (1; no re-wiring is needed & 2; they want 4 blower speeds.) The controller conversion is very involved and requires a LOT more work for very little benefit.

Just install the non-AC box, re-use the original (4 speed ) resistor pack, find a new mounting spot for the high speed relay and plug in everything possible while tucking in the rest.

Last week I was wondering about the radio capacitor myself. My Digital speedo acts weird @ start-up and I might use this as a guinea-pig ( as well as trying a 'tach filter') to try and correct that Speedo glitch. Sorry; Back to the point !!!!!!



I've only seen the capacitor used on the real early Thirdgens,... 82& MAYBE 83 I'd guess. IIRC the 82's used a "square" resistor pack but later years used one the was shaped more like the letter "D". As you can see this thing is just an in-line capacitor and might help getting you some better radio reception when the Blower is running. I wonder if this capacitor was only used with non-AC cars ????

 

That's funny. I had forgotten about that capacitor. I think my 82 Z28 (non AC parts car) had it.

As for wiring, the non AC heater box that I have is cut for a 3-resistor harness. I'd have to modify the box to accept the 4-wire pack. That isn't a big deal one way or the other although having 3 speeds is fine by me.
What I do find interesting is that in high speed, the AC blower is driven by way of a relay, activated by the head unit speed switch whereas the non AC high speed function is driven through the speed selector. There is no relay. What this tells me is that the non AC selector is probably more robust and can handle the increased current. It would be convenient (and tidy) to just connect the orange wire from the AC harness directly to the blower but I'm not sure the switch could handle the current.
The other wiring difference I see is that in the non AC application, the 25 amp fuse in the fuse block handles all of the current duties for the blower speeds. The AC version will switch to power coming directly from the fusible link when high speed is called. This leads to the question, is the AC blower of a higher capacity that the non AC blower? And if it is, is it possible to run the non AC blower through the AC selector switch (as it's done in lower speeds of both applications) and avoid the added bulk of the relay wiring?

 

AC System: The Orange (switched power) wire is shown sized as a '1',..... the Red power supply to the high speed relay (and the purple wire feeding the blower directly) are sized @ a '3'. Even in the non AC set-ups the power wire supplying the blower directly is a '2'. I doubt the AC controllers '1' orange wire will hold up for long if directly supplying the blower.


There is a specific blower motor used for AC OR non-AC applications (& IIRC the AC unit is larger. ) I'm guessing that they have different rating,... that's a guess !

Removing the relay and a couple extra wires simply isn't worth it to - almost anyone. It's SOOOOOOooooooo easy to just the install the non-AC box with the AC resistor pack / AC harness & then go do burn-outs again and never have to worry about starting fires......... why make things complicated ?? ( Because of a relay and 3 wires ?? )



If you feel compelled to remove the high speed relay and it's (heavy gauge) wiring,.... I'd suggest re-pinning a larger gauge wire to replace the ORANGE wire leading from the AC controller to the 3-speed non-AC resistor pack.

If you plan to install the AC resistor pack, use a relay. If the relay is that much of a "eye-sore",..... Hide the relay.

 

I wouldn't risk burning up the head unit switch.
I'll just rewire it as if it's an AC system. If I can get the 4 resistor pack into the 3 resistor space with little trouble then I will. Otherwise I'll have to survive with 3 fan speeds. Seeing as I've been driving for the last several seasons with only 2 fan speeds, it'll be a whole new experience! The power for the blower's high speed is still there in the form of the fusible link connection that also used to power the under hood light. Good enough spot for a relay too. With the exception of the ground for the coil of the relay, all the wiring is there.
Then I can go and do burnouts (after I've finished putting together the top of the engine...)
Thanks for the insights.