Hi all. Its time for the latest installment in the saga of "What the heck is he doing NOW?" As one of my winter projects I plan to try to free up the stuck flaps in my heater box. I think that as in another thread i saw, they are rusted to the housing but am not sure. My cables seem to be ok. I have the Jag shop manual which says to remove the bonnet in order to remove the heater box. I am wondering if there is a way to get at the flaps without removing major body parts (mine or the cars) and possibly only dislodge the unit rather than completely removing it. I would feel somewhat more secure for instance removing the instrument panel if that would give the required access. Any thoughts or potshots?

 

all i know is that years ago I removed a complete heater box in one piece from a S type parts car without removing the bonnet or dash. And without a service manual.

can't remember if I had to get under the pedal box or not, which I also removed.

 

Cass had his heater box out in the not too distant past. I'm sure he can advise. You certainly don't require to remove the dash. It comes out from the engine compartment. I'm sure you can get it out without removing the bonnet. Might just be a little more difficult. LHD you have the clutch & brake master cylinders to contend with. There are just 2 rubber pipes & a foam gasket IIRC it presses against to take air into the cabin system & the large fan hole. Held on as you can see by tabs & bolts.

bonnet on:

 

Excellent. Thanks. I know the "official" manual will tend to overwork a guy like me. I was also thinking that the airflow hole may be large enough to at least reach through with a scraper to work one of them loose.

 

I would remove the box, blast it clean and the core, replace all the seals, etc. if you want a nice working heater.

the heater tap / valve can be replaced with any normally closed, opens with vacuum valve. In my S type I use a replacement heater valve for a 1965 Ford Galaxy, plastic, made in China, works fine if not better. Sold at Autozone, O'Reilly, Advance Auto Parts, etc. Very simple heater system, cable and vacuum operated. And contrary to what I have read, quite efficient in winter (in my experience), once the coolant is hot.

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As Glyn says the heater box is removed from the engine bay. There is no access to it from inside the car. The holes through the bulkhead are too small for your hands and to to even get to the holes from inside the car would mean on a LHD car removing the steering column, Main gauges and wooden dash.
Removing the bonnet is not necessary but if you want piece of mind and room to work essential. Five minutes, four 7/16 bolts, a mates help and the bonnet off gives so much more room to work.
Heater is held on to the bulkhead by I think 7 7/16 bolts. You will need a small headed 7/16th socket on a long extension bar. Disconnect the two water inlet pipes and the hard part is getting at the heater control cable. It is tucked down the left side and it is difficult to see what you are doing.
It is worth removing the heater box to free up the levers and flaps. They are piano hinges and need a lot of lubricant and working to get the stuff freed up. Really best to be done on a bench. Whilst there you will find all the internal flap foam seals will be rotten so will need replacing. No replacement seals to be bought so I had some 5mm closed cell foam lying around and cut some new seals to fit. You can buy it on EBay with a sticky backing so great to fit.
There are round foam seals on the bulkhead which you can buy replacements for I believe but I used the 5mm closed cell foam again to make my own. They cannot be seen once in place to pointless paying a fortune for original seals.
Lastly stick a hose in the end of one of the water pipes on the matrix and give it a good flush out. It will run for about three minutes spouting brown rusty water before it runs clear.
This is a photo of the bulkhead behind the heater. The large hole to the left is the fresh air hole from the scuttle to the fan motor. No access to this from inside the car. The two holes bottom right with the black rubber seals are for the Hot air ducts to the screen demisters and as you can see they are too small for a hand to get through. The large oblong hole at the bottom is the main air vent into the cabin which lines up with your sticking vents and again you can clearly see there is no access from the cabin to this point.

 

Good advise. Im pretty sure it needs a good swabbing out after sitting for... however long it was. Ill be trying it eventually. I just dont want to have to track down another due to my own ignorance. As an aside, I see the resistor on the fan motor is more or less integral to the motor- I mean there doesnt seem to be a plug for it (and no separate part number), so replacing is a matter of clipping wire. Any suggestions on a replacement resistor? I would think any heater fan one would work even if it was a multi speed one. Just a matter of using the correct resistance....

 

Yes! Thanks Cass. That is the pic I was hoping for. You were sending just as I was. I suggested going at it from inside because even though I could (sort of) see there wouldnt be much room, Id rather do that than remove the hood. As a plus, the red and the white cars make it so much easier to see than down in the abyss of my dark green.

 

I don't know the value but the heavy wirewound resistors last forever. I would not replace unless necessary. Unless yours is MIA just measure it's value if you feel you must replace it. I kept my original green one.

I stripped mine down, sandblasted the box & powder coated. Replaced every seal, foam & rubber elbow (in those 2 small holes) ~ then reupholstered. Resprayed fan & fanmotor. Lubricated everything. Reassembled then fitted.

BTW ~ I sent my heat exchanger for chemical cleaning & pressure testing ~ all OK & I have a spare. They are copper so long lived but need to be kept clean & corrosion free with proper coolant. The engine compartment feed pipes are steel & rust. Replaced mine with new stainless steel items.

Sorry I keep adding to this. The main heater cable control & lever are underneath the chromed centre grill on the parcel shelf. Remove grill for access.

 

Like Glyn my resister was fine so I left it alone.
Yes photos of a white car especially around the engine bay are a lot clearer than any dark colour. When I did my rebuild I took loads so if you need anything else give me a shout.