Heater Air Flow

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
First, does anyone know of an alternative PN for a resistor other than the $$$ LR version?

Second, airflow.... This is an NAS 110 style dash with the blower vents, not the fresh air vent doors. The bulkhead already had the larger opening in it. On the engine side, I have a standard (non-A/C) box and blower set up. This saves room, is much cheaper, and there just isn't any need to have all that in the engine bay if you don't have A/C.

So picture this: The air comes through the bulkhead. It enters the lower dash, it is pushed through the dash and up into the center dash where the louvers point it at the peoples in the vehicle. Along the way, some of that air is directed either up or down--just like in normal Defenders. So, if you think about it, something like 1/2 of the air flow is ALWAYS going up or down, while 1/2 is always going out the vents. And what is really strange is that no matter what, the air temp coming out of the front vents is always 10-15 degrees warmer than the air coming out of the footwell vents, or defrost vents! What? It's all the same air coming out of the same box, through the same hole in the bulkhead!

Now, I'm sure the designers of this high tech system thought they would be generating laminar flow within the dark recesses of the lower dash body, but somehow I doubt that their design dreams are fully realized.

So the question is, other than a better fan, is there any way to increase flow through and around the obstacles and eddy current generators within the ducting system? And does anyone have any idea on how I might equalize the temps coming out of the vents?
 

4RF RDS

Well-known member
Change the bottom vent ducts with a closable louvre and get some covers for the defroster vents for when they are not needed. Just open what you want and never use the lever again. Did this to one of mine and it worked great. I actually removed the flaps for the lower vents inside the lower dash.
 

NPT90

Well-known member
Weirdly enough the AC setup sort of addresses this by redirecting the air for the footwells through a set of vents at the knees. Best bet is to get the bulkhead gasket sorted, and plug all the bulkhead holes. There is also a gasket between the air intake on the wing and the heater box (basic foam) that's usually gone.

honestly the stock setup works well enough if you pug all the holes. I replaced the bulkhead gasket and that piece of foam and I get plenty of hot air.

As far as that resistor goes I ended up sourcing a TD5 heater box instead of trying to buy one of those resistors, they are insanely expensive
 
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