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Seat Headrest, Tonneau Pins, Heater Function  Rate Topic 
 Posted: 09-23-2005 10:46 pm
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1st Post

Joined: 07-06-2005
Location: Eugene, Oregon USA
Posts: 162
Hello, folks.  Two minor questions:

Is there some trick to getting the headrests to go up on the stock seats?  I've seen pictures of them up online, but I can't get mine to budge.

Also, I'm missing one of the windscreen frame tonneau pins.  Are those available from stores?  Does anyone have one they'd be willing to part with?  Are they too expensive to bother with?

Finally, can anyone give me a quick rundown on the operation of the heater?  The lower lever moves a baffle on the heater box behind the dash, but I'm not sure what it's baffling.  The other lever seems to hit a vacuum switch that is connected to the heater coolant line, but does it also open/close a butterfly valve or something as well?

Thanks for everyone posting on this board; I've learned a ton of stuff just poking around on old posts.  I'm glad the JH community is so positive about teaching and communicating.

Last edited on 09-23-2005 10:47 pm by edward_davis

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 Posted: 09-24-2005 01:28 am
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Mark Rosenbaum

Joined: 03-12-2005
Location: Kingman, Arizona USA
Posts: 532
Moving the headrest takes some effort, or, if things are badly rusted, brute force.  The headrest is normally held in position by a roller thing in the seat back, using a springy wire center, that presses against the wider face of the shaft.  The bottom end of the shaft has a thin sheet metal D-shaped spring that protrudes from the side and which is supposed to keep the headrest from being pulled all the way out.

Tonneau pin.
These are also known as 'Lift-the-dot' posts and were commonly seen on most British cars of the period.  If nobody with a parts car has a spare, you should be able to find some by checking with the various suppliers.  They shouldn't be very expensive, even today.

Heater function.
Examining my spare heater as I write this, here's what I see:

The upper (shorter, up-and-forward pointing) heater lever determines how much of the air from the fan goes through the heater core and how much goes directly to the lower part of the heater.
* When the heater lever is all the way up/back, all the air goes to the heater core and to the port for the ball vents.  This is the 'HOT___OFF' position of the dash upper lever (and should be thought of as 'HOT or OFF').  (Note that in cars with air conditioning, the ball vent ports were capped off and the ball vents received cold air from the A/C.  Some cars also had an additional small port in the lower dash to the left of the steering wheel.)
* When the heater lever is all the way down/forward, all the air goes to the lower chamber of the heater and none goes through the heater core.  This is the 'COLD' position of the dash upper lever.  Here, for late cars, the heater lever would also operate the plunger on the vacuum valve that controls the inline water valve in the engine bay.  (This valve slips into a bracket that is not present on heater boxes for earlier cars.) 

The lower (longer, rear pointing) heater lever determines the destination of the air from the heater core.
* When the heater lever is all the way up, the hot air outlet of the heater core is sealed shut and the lower chamber is open to the cockpit.  Meanwhile, the position of the upper lever determines whether or not fan air is applied to the lower chamber.  This is the 'OFF' position of the dash lower lever.
* When the heater lever is parallel to the bottom of the heater box, the lower chamber is sealed off and all air from the heater core and/or fan-and-plenum is applied to the defroster vents.  This is the 'DEFROST' position of the dash lower lever.
* When the lever is moved further down, the flap pushes past the bottom of the heater box.  Here, the heater's lower chamber is again open to the cockpit, but hot air from the heater core can now flow both to the defroster vents and into the cockpit.  This is the 'INTERIOR' position of the dash lower lever.

The heater control cables are of fixed lengths, so the only way the heater can be made to operate as intended is to clip the cable sheathes to the heater box and dash quadrant at the proper spots.  AFAIK the proper locations can be determined only by experiment, which probably means that it will be necessary for the quadrant to be separated from the heater console.  A permanent marker can be used to indicate the correct cable securing locations, once these are determined, and the heater and heater console can then be installed in the car.

The clips securing the heater cables in place are the same as the clip used for the choke cable.  These can lose tension and allow a cable sheath to slip, or can rust and break, or can slip free and fly away if not correctly installed.  It's prudent to have a spare on hand.  Replacements are readily available from Delta Motorsports.

NOTE: The parts manual drawing that shows the hookup of the control cables to the heater is not correct.  This drawing would have the dash 'temperature' lever operating the heater's 'air distribution' lever, and vice versa.


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