'68 fresh air blower/heat questions (long)

[dotorg]

Fall has gotten chilly, and I'm on a quest to finally understand the heating/cooling in this damn car.

Right now I've got two problems -- my heat only marginally works, and I seem to have some sort of a ram-air induction system scooping frigid fall air and blowing it out the center defroster vent in the dash. The heat worked way too well when I first test drove the car (mid-summer). There were no heater flapper boxes, so it seemed to be channeling hot air from the engine bay and scalding legs left and right...

That was unacceptable for the summer, of course, so the P.O. had his mechanic put the flapper boxes in place, so at least I wouldn't get scalded. The flapper box cables though weren't hooked up for several months because I didn't have the hose clamps the cables fit into.

A month ago I finally hooked up the passenger side flapper box (the guy installed the control cable wrong and there just isn't enough slack on the drivers side cable to fit, so I need to eventually trim back the sheath so the cable sticks another inch out of the cable sheath itself). I discovered that even with the control handle all the way up, I now only get a trickle of warm air through there, not the blistering hot air I had when nothing was hooked up at all.

How is the heater plumbing pressurized? I assumed the alternator fan pressurized that plastic sheath over the motor and somehow channeled the air down into the heat exchangers, and back to the cabin via the flapper boxes, but I'm unclear why I wouldn't be getting any air pressure now. (Now admittedly I got blasted by hot air on the drivers side before, so I imagine its possible the duct on the passenger side is blocked... does that ever happen?) Would I not get pressure because only one flapper box is closed?

Being unclear how this all is supposed to work, I decided to finally hook up the fresh air blower thats in the smuggler's box. I'm totally baffled by this one, though. The P.O's mechanic had torn the hose that goes from the blower, over the steering column and into a box tucked up under the dash on the drivers side when he was installing it. I finally got a replacement from him and installed it yesterday. Now when the blower is on I get air blowing out side defroster vents in the dash I didn't even know were there, and none out the center vent, which makes me think I didn't fix my blast of cold air problem... I had been guessing the trunk was pressurizing and the cold air was coming through that open vent in the trunk that now has the hose on it.

So now I have two problems...

First, the hose that runs from the blower in the smugglers box , through a hole in the floor of the trunk, across the steering column and into that vent actually is in contact with the "knuckle" (brain fart this morning, cant' remember what its called), where the steering column zigs from the dash more downward to the steering rack itself. It doesn't bind the steering or anything, but I have to assume its going to wear a hole in that hose. How is the blower actually mounted and aligned in the smuggler's box? (I can't find any info on this thing anywhere!) It seems if the whole unit could be rotated ten degrees it would move the hose far enough to the side to not rub. Feeling down on the bottom of the blower, it seems to go right though the floor of the smuggler's box, but I can't see a damn thing to know whats going on down there.

The second problem is the blower used to work on two speeds, and doesn't now. I'm not sure what I broke. The wiring seems confusing at best, and its not in the car's wiring diagram so I've got no idea if the P.O. or his mechanic wired it up wrong. There are three contacts on a bracket that seems to be supporting the blower. The closest to the blower appears to be grounded. The other two were disconnected. One wire runs from a relay that is clearly not original to the car into and one runs from the switch in the dash. The switch itself only works with the knob all the way out (in its "high" setting). Depending on the order I wire those two wires into the blower, that setting is either low or high. The low switch setting does nothing.

Adding to my irritation, I discovered my hazards no longer work. I hope its not related to my monkeying around yesterday!

On a related note, anyone know what the third round knob is on the dash next to the hazards? I have three round knobs above the radio/cigarrette lighter -- a two-stop blower control, a one-stop lighted hazard knob (which doesn't work) and a third on the left that doesn't do a damn thing.

I ignored electrical stuff most of the summer because of how frustrated I got last time I tried to get this stuff working... I dread figuring out what is wired where when I install my xenarcs this week...

[dotorg]

weekday bump

[Rot 911]

Damn that is a long post. First of all the fresh air blower does nothing but that: blow in fresh air, which means in the winter time, cold air. The heated air comes, as you discovered, from the engine cooling fan, through the heat exchangers and into the cabin via hoses off the heat exchangers through the inner rocker boxes and out into the cabin. I am not sure if you have the 3 lever heating/cooling system on your dash, but assuming you do have them, they work as follows:
Top lever: controls the amount of fresh air that comes into the cabin (on some models is also connected to the fresh air blower fan), left is all the way closed, right is all the way open.
Middle lever: directs where the fresh air goes. Left directs air down, right directs air up up.
Bottom lever: directs where the heated air goes. Works same as middle lever.
Got all that? Now to make sure you get heat into the cabin you need three things working: hoses from fan housing to heat exhchangers with no holes and properly connected, hoses from heat exchangers to inner rocker panels with no holes and properly connected and finally the flapper boxes need to be completely closed, that is, when you are looking at them you can see the slots that would allow the air to escape under the car are completely covered. Do this visual inspection and report back. Keep in mind that at idle all you are going to get is a trickle of air. At higher rpm's the air will increase along with the heat.
As for that third knob, if it has some squiggly lines on it, it is probably your rear defroster. Should be a two stage pull out knob.

[ValveFloat]

Right now I've got two problems -- my heat only marginally works, and I seem to have some sort of a ram-air induction system scooping frigid fall air and blowing it out the center defroster vent in the dash.

I think this air is coming from the vent in the cowl. There should be a lever on the dash about below the clock. If I remember right with the lever to the left you get fresh air through the defrost vents. With the lever to the right the air should come from the blower.

How is the heater plumbing pressurized? I assumed the alternator fan pressurized that plastic sheath over the motor and somehow channeled the air down into the heat exchangers, and back to the cabin via the flapper boxes, but I'm unclear why I wouldn't be getting any air pressure now.

The heat exchangers are pressurized by the cooling fan. There should be a flexible hose running from the fan housing on each side of the engine down through the sheet metal to the rear of the heat exchangers. Those hoses might be leaking. Then there should be a short section of flexible hose from the front of each heat exchanger to each heat valve. Check those hoses too.
I'll have to look at my car tonight to see how the blower is plumbed, and I'll take a look at the wiring too.
My hazards have never worked, if you figure that out let me know

On a related note, anyone know what the third round knob is on the dash next to the hazards?

On my car that switch is for the fog/driving lights

[1yearonLy]

Nice to see another 911L in the mix Valvefloat! Welcome.

Have any interior pics to post?

[1yearonLy]

Oh, and a pic of my dash knobs if it helps:



(I have replacements coming for the darkened/faded ones).

[dotorg]

Hmmm, the fog/driving lights are controlled by a knob all the way on the very left of the dash, immediately beside the headlight knob. Its only got a small amber light on it, too. In fact none of my knobs have those icons on them, weird.

Do you have two knobs to the left of the steering column? If so, what do they do?

I suspect now that my lack of heat was caused by the control cable popping out of the one flapper box that was actually hooked up. I didn't drive the car today, but I tightened up that one and finally hooked up the other side and will see if that helps with the warm air.

The control under the clock which I assumed did, in fact, control what air was goign through those dash vents doesn't seem to do a thing. Maybe its disconnected behind the dash. Does the hook cowl vent do anything other than fresh air intake? I assume not? I might just cover it or something...

I'm still baffled by the wiring. Every time I go deeper into the car, less stuff matches the wiring diagrams.

[1yearonLy]

To the left of my wheel I just have the ignition switch and headlight switch.

The other 3 knobs (as shown earlier) are to the right of the ashtray.

I do have a cigarette lighter and some rotary knob just to the right of the steering clamshell.

[dotorg]

Weird, wonder why they are different? I actually have fiveswitches to the left of the steering wheel -- ignition, headlights, foglights and a toggle switch for the sunroof, and one I believe did either the rear defogger or the rear wiper. (Neither work, so I'm not sure which of the two it was hooked up to).

I have the cigarette lighter and a hole where a switch was that was wired to the power antenna (now empty, since I put a manual antenna in).

[1yearonLy]

pics...

[dotorg]

Wow, even stranger, my ignition switch is totally different, too. Its got a big black surround. My ashtray has a much smaller handle on it, too.

I wonder if its a Euro vs US difference? (I recently found that the VIN of my car is from a ROW 911L, not a US 911L, explaining why I've got metric/german gauges)

[1yearonLy]

My ignition switch seems to be missing the surround...it should have one.

[ValveFloat]

Ok, here are some pics of my L.
Click on them for a larger picture:


It looks like a hose clamp is used to keep the hose away from the u-joint.

And just for fun, one of the newly rebuilt engine:

[dotorg]

Ooo, you've got an extra wire on your blower. I've got three, you've got four...

Any idea where those wires go from there? If they go direct to your switch, any chance you could take a peek and tell me which of those colors goes to which tab on the back of the switch? Brown, red, black... I'm convinced someone in the past totally rewired this damn car.

Still baffled by the interior, though. My dash is totally different. Bizarre.

Whats that extra wire in there?

[1yearonLy]

Nice pics, thanks for posting. It is a great reference other '68 owners like myself.

Here's a dumb question: Is that heater blower thing standard on all 911Ls? I wonder if I have one in that little covered area...I never looked. Should I? I know I have that fan switch on my dash...

[dotorg]

I have no idea, but I assume its not standard, because there's no wiring for it on the 911L wiring diagram.

[1yearonLy]

I don't really use mine since I'm in California. if it gets cold I pull the little lever between the seats and the heater comes on just fine.

I noticed from Valvefloat's pics that our dashes and interior are basically identical except for the patern to the dash covering. Our doorpanels match as does everything else. Ours must be US cars and the ROW cars must be indeed different. I know the guages are...the ones recently on eBay were from a euro '68 911L. I have pics if needed.

[ValveFloat]

Since there are two red wires at the switch I don't know which is power in and which one goes to the fan. I can check later with a voltmeter if it would help. I'm not sure why there are two ground wires at the fan either.
The extra wire (orange) in there is power to the Holley fuel pump, you can just barely see it behind the fan motor.
I was under the impression that all 68s have the fan.

[dotorg]

So the black and red on the blower go to the switch, the brown is just grounded somewhere else, too? And the other red on the switch I presume goes to power elsewhere...

That sounds like how mine is wired up, but my wires are definitely not on those tabs on it. I'll have to take a look when I get home. It'd be exciting to have one electrical problem finally crossed off my growing list!

[1yearonLy]

I'll have to look in my 'smugglers box' and see if I have one. If so I'll take some pics and report back...