Thread: P38 HEVAC Unit

Originally Posted by SSchiwy

My car has heated seats but I am told that will be a tall order.

Yes, most don't have the heated seat switches. I believe it's possible to modify the panels to accept the switches from a panel that does have them.

I think there are different model panels, too. I may have one in my spares (but I could have passed it onto a friend. I'd have to check).

This thread may help Climate Control Fix (pictures) | Range Rovers Forum The pix are terrible.

The write-up I did years ago has been deleted from RangeRovers.net.

Hi There,

Dirty connectors would probably prevent the blend flaps from working properly but it is usually the servos that go (broken teeth and/or worn out pot's). The display can be repaired with a bit of patience. There are indeed repair kits floating around. Make no mistake, the dirty or loose connectors that prevent your display from working (for which there is a repair kit) are not the same as the connectors on the outside of the unit Also, if there is a testbook signal in the display the unit won't send a signal no The computer has detected a fault and won't even try to move the servos anymore, you would need to reset the computer or use a nanocom or whatever supports it to force the units to move.

If your car has heated seats but not the buttons for it, it is an easy fix if you do not mind making a button for it yourself. You can test them simply by tapping a wire on the connector. I will try and remember to look that up for you when I get back tonight! (ties knot in handkerchief) You should hear a relais click and the seat should get warm, eventually. Personally I would not hold my breath since the RR heated seats are notorious for breaking all the time. I fixed mine once, they broke already again. The problem is the connecting wire between the seat and backrest gets crushed by human activity and it simply fails / burns out. You can repair it, like I said but you would need to remove the entire seat lining. Land rover replacements break just as fast so still not worth it imho.

Finally, always an expensive thing to resort to I guess but in europe most if not all of them had heated seats. Since RPI is also a wrecker of some sorts they might have a head unit with heated seat buttons? Keep in mind that you get the right part though! the older ones used to power the AC clutch directly, the newer version only powered a relais in the engine bay. They are not interchangeable (ask me how I know ) I ended up making a relais for the clutch myself since my unit would drop the voltage too much, never had a problem since.

Cheers,
-P

If you are looking second hand from the UK my suggestion would be to look on EBay UK to see who is wrecking what you are looking for. There is a mixture of both private people breaking one vehicle and wreckers yards advertising. You will see the adds often with the sale of one wheel nut. You contact them for the part you want. If necessary get them to post it to me and I can post on to you

There's different HEVAC units for different years and they're not interchangeable. I would assume with heated seats that you have a later car though.

On connector C246b pins 19 and 20 respectively are the seat heater request line for RH and LH heated seat. (see the image here: https://www.startpage.com/av/proxy-i...176e3a5ada8457)

You need to of course look on the wiring loom side but same difference. Heated seats are controlled through the BECM (what isn't) and when the request line is up the BECM will send a signal to the stations that are under the seats to turn them on. I have the BECM side connections as well but let's just start here I guess?

Cheers,
-P

Originally Posted by prelude

Hi There,

Dirty connectors would probably prevent the blend flaps from working properly but it is usually the servos that go (broken teeth and/or worn out pot's). The display can be repaired with a bit of patience. There are indeed repair kits floating around. Make no mistake, the dirty or loose connectors that prevent your display from working (for which there is a repair kit) are not the same as the connectors on the outside of the unit Also, if there is a testbook signal in the display the unit won't send a signal no The computer has detected a fault and won't even try to move the servos anymore, you would need to reset the computer or use a nanocom or whatever supports it to force the units to move.

If your car has heated seats but not the buttons for it, it is an easy fix if you do not mind making a button for it yourself. You can test them simply by tapping a wire on the connector. I will try and remember to look that up for you when I get back tonight! (ties knot in handkerchief) You should hear a relais click and the seat should get warm, eventually. Personally I would not hold my breath since the RR heated seats are notorious for breaking all the time. I fixed mine once, they broke already again. The problem is the connecting wire between the seat and backrest gets crushed by human activity and it simply fails / burns out. You can repair it, like I said but you would need to remove the entire seat lining. Land rover replacements break just as fast so still not worth it imho.

Finally, always an expensive thing to resort to I guess but in europe most if not all of them had heated seats. Since RPI is also a wrecker of some sorts they might have a head unit with heated seat buttons? Keep in mind that you get the right part though! the older ones used to power the AC clutch directly, the newer version only powered a relais in the engine bay. They are not interchangeable (ask me how I know ) I ended up making a relais for the clutch myself since my unit would drop the voltage too much, never had a problem since.

Cheers,
-P

Many thanks for your detailed and supportive responses Prelude, Scouse and 3toes

Many thanks to Prelude, Scouse and 3toes for your helpful responses. Next stop for me is a phonecall to RPI (they have not responded to my inquiry yet) and getting into EBAY UK. I have also identified a business in Sydney that repairs units like HEVACs to see what they can do, cheers, Simon

I wonder if Lee Bourgeois in Mittagong (LAB Electronics for Land Rover P38s, aerial brackets, towing trailers with LEDs) repairs the HEVAC panel. It's not mentioned on his website but it could be worth a call to Lee.