Pre-req: you will need working blend motors/flaps and distribution flaps, and the engine warmed up, and the interior warm.

In my P38, I have a strange thing happening. If I have the HEVAC set to say 22c, and the air set to come out of the face and footwell vents, once the temperature in the car reaches the set temp, the air from the dash cools off a bit as it should, but the air coming from the footwell vents is constantly hot. If I set the air to only come out of the footwell vents, its also always hot. This becomes a bit uncomfortable after a while, unless I set the air to only come out via face or screen vents. The air does go cold from the footwells if I set the temperature quite low though.

What does your car do? I don't know if I've cocked up rebuilding the heater box, I'm pretty sure I haven't. Blend motors are calibrated, though really shouldn't make a difference as the temperature coming from each vent (per side anyway) should be the same regardless of what the HEVAC thinks, and the distribution works fine.

Looking at the old one, the air to the footwells goes back down over the back of the heater core section, which I guess could be warming it up, but I wouldn't have thought enough to keep it properly hot.

You could just put it on Auto :)
I'll have a play with mine tomorrow, but can't guarantee that its working as it should!

If I leave it on auto, once its warmed up, I continue to get roasted feet, and cool air out the face/screen...

I put my pre-requisite because I know a lot of P38s have HEVAC issues, but I wasn't quite expecting this lack of volunteers :) I jest.

Mine behaves itself up to 20°C on auto, which is as hot as I ever run it.

Have you checked the cabin temperature sensor fan runs properly and that there is no fur or dust insulating the sensor itself. Both my SAAB 9000 hatchbacks came with similar heat distribution issues. Cured when I unjammed the fan on one and cleaned out seriously furred sensors on both. Big balls of lint'n crap on them. I suspect there is a fallback setting inside which limits how hot the face air can get if the system inputs are out of range. SAAB certainly had one.

Clive

Sensor is free of crud and it reports a reasonable temperature. It just seems no matter what temperature the inside of the car actually is, I get hot air at my feet. Unless I set it really low, then it will go cool. If I have the airflow set to both feet and face, to start with, when the interior is cold, I'll get hot air from both. Once the interior gets up to temperature, the face vents cool off... but my feet continue to roast.

This should not be possible...

That's what I was thinking. As far as I can work out, the temperature blend motors adjust the airflow through or around the matrix so that sets the air temperature and the distribution blend motor directs where it comes out. I've always assumed that the air will be the same temperature no matter where it is coming out from. If, as on mine, your feet were getting cold, then that is when the duct joints leak so air escapes onto your feet before it even gets as far as the heater box but not hot air on your feet and not on your face. Sure it isn't your gout playing up?

-_- cheek!

My ducts are all nicely sealed up - I took advantage of having the dash out and arrived at Marty's with draft excluder and duct tape!

I have no idea how I've managed it if this isn't normal. Even if I'd not lined up the distribution flaps properly, that would just mean I'd have air coming out of places on the wrong settings... but they all behave as they should. The only thing I can think is that where the footwell air passes back over the rear of the matrix section, when air is passing through said section, its heating up the rear plastic, and then the footwell air is being heated by that. But it seems very hot for that amount of heat exchange to be going on...

This is the bit I mean, with the front panel that keeps the air going down to the vents in place.

I've not replied, cos I get in, turn heater on, if it works I'm happy, I wear boots all year so feet are always warm, I leave mine on demise, apart from once a month I cycle it through all the other settings to keep motors free

Sloth wrote:

I put my pre-requisite because I know a lot of P38s have HEVAC issues, but I wasn't quite expecting this lack of volunteers :) I jest.

Sadly, I can only meet one of your pre-reqs - Engine Warmed Up. Sorry!
(20 degrees cabin temperature is a distant memory)

I'll get some draft excluder in for my trip to Marty, top tip.

Well after experimentation, my GEMS delivers cold air to feet and hot to head. Might not be a true reflection as aircon comp is bypassed.
On the Vogue it seems balanced warm between head and feet, but because the display is now dark I can only guess settings from the switch illumination.
All in all I haven't really been much help, I'm afraid!

Hahaha

Why do we own these things?

I've had a thought how I might go about 'solving' this... I might just partially block up the front footwell vents. Firstly reduces the roasting of my feet, and also forces more air back to the rear underseat vents.

Just been out in mine and probably not a fair test as it's a whole 1 degree outside so I need the heater. However, I know that in warmer weather, once mine has the car interior up to a comfortable temperature, the air from the face vents cools off but I've never bothered to check to see what is coming out of the footwell vents. This evening, it started off blowing lots of hot air out of both face and footwell vents. Once the interior of the car was at a reasonable temperature, the face vent output went down to very little but still lots of nice warm air at the footwell to keep the interior warm and my feet nice and toasty. I would assume once the interior temperature was up then the air to the feet would cool down too (but it's unlikely to do that at the moment).

I don't have rear underseat vents as Mr plod didn't need heat in the back so the output for these vents are blanked off. Didn't realise this at first but it does explain why I wondered what the problem was with getting access to the blend motors and O rings as I don't have the duct that gets in the way.

I think I've only tried mine on cold days - it is comparatively tropical here at the moment. Maybe I'll take it to work tomorrow and see how it behaves being almost in double-digits outside. Maybe it will cool off a bit.

I'm pretty sure mine does what I tell it to.

I quite often get reports of cold feet from the other side of car and have to crank the foot temperature up and then back down again accordingly, until a happy temperature is found.

It lives on Auto the rest of the time though.

I can have a play with it on Friday as we're heading all the way down the Chippenham.

This is actually driving me mad now. The top vents (either face or screen) are going properly cold (not full on air conditioned cold, but cold enough it feels like ambient outside cold) compared to the feet and I actually feel like I'm in different climate zones unless.

The air goes where its supposed to... I just get wildly different temperatures.

Had the nanocom plugged in just now and the only thing of note is the aspirator temp seems pretty optimistic, but regardless of whether it was actually 24c inside the car or not, I'd expect (and want) the air to be the same top and bottom, not roasting my feet while delivering a cool breeze up top...

Right it isn't heat coming off the back of the heater core - drilled a small hole at the top of the rear panel just before the air starts passing over the heater core, stuck a thermocouple in, and its hot up there as soon as the air starts coming over.

What the hell have I done... to confuse things further, the passenger side dash vents are also colder than the drivers side. But both footwells seem to be the same.

What I have found is that with the blend motors on anything less than 100% (ie, hi/hi), the dash vents are cold once the interior has warmed up. As in, they are at least 10 degrees cooler than the footwells. That's shit. Looks like the dash is coming back out again. I'm getting mighty fed up.

Why not just go with Plan A and partially bung up footwell ports until summer? Give you something to do on those long hot languid summer evenings...

I think if I do that, I won't get much heat in the car at all. If I set the air to come out of the screen/face vents once its warmed up, I then continue to just get cool air from them and not much in the way of heat, despite the blend motors staying at 80%.

Other option I suppose is close all the face vents and see if lowering the temperature convinces it to stop roasting my feet. Then hope that the cool air keeps the screen clear. Just slightly annoying having freed up the heater box, swapped the heater core, put new blend motors in the thing, its still being a pain in the arse.

Or, I say fuck it, leave it on hi/hi and just turn the blower down to bugger all myself once its warm, accepting it as another piece of quality LR design.

I cannot see how I've gotten the heater box put together in some wrong way... it just doesn't seem possible. The air goes where its supposed to on demand, and I can have it hot or cold. Apparently, extending into both hot and cold simultaneously at its own discretion.

I LOVE my E39's climate control. I can have air wherever I want it front, back, top or bottom, or I can truly leave it to fend for itself. I can even have different temperature air from the centre console vents if I so wish. It'll roast you evenly from head to toe, or freeze your bollocks off in the height of summer, whatever you fancy! Not surprising LR built the L322 from the E39 5 series and E53 X5...