P38 HEVAC Unit

[SSchiwy]

Good afternoon,

looking for advice on HEVAC units - mine has been tested by an auto electrician in Canberra. Apparently not sending a signal to the motors controlling the flaps/blending. The LCD screen is also dodgy. Drivers side blows warm air, passenger side blowing cold air.

Have seen a sight in England - RPI Engineering that sells 'zebra kits' which they say will fix the LCD screen issues. If the connectors are cleaned up would that also assist with sending the signal to conrol the flaps/blending?

Have been in contact with Triumph Rover reckers in Adelaide and they dont have any second hand units.

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

So looking for some wisdom of next steps, and/or if anyone has advice on a good repairer.

All advice gratefully appreciated,

Cheers, Simon

[p38arover]

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 (https://www.rangerovers.net/threads/climate-control-fix-pictures.20591/) The pix are terrible.

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

[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 [bighmmm]) 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

[3toes]

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

[Scouse]

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.

[prelude]

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-image?piurl=https%3A%2F%2Fwww.rangerovers.net%2Fat tachments%2Fp38-rr-hevac-unit-z253-hevac-jpg.10467%2F&sp=1688715875T374d58409278ac580b8b09a892984b467378 c4715dc8886a58176e3a5ada8457)

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

[SSchiwy]

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 [bighmmm]) 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

[SSchiwy]

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

[p38arover]

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

[SSchiwy]

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 Many thanks Wizard - may have to take you up on your kind offer but still working the issue!

[garybrook]

Hi Simon,

I had to repair my HEVAC on my 2000 P38 as some sections of the screen had failed earlier. I bought the zebra part from the UK so I safely stripped the body from the back of the harness and it eventually worked, after about 4 attempts. The zebra is fragile as are the electronics, but itÂ’s doable as mine is still working after 5+ years since the repair. IÂ’m not sure but I may have bought another spare zebra, just in case - which is usual to me as the experience of maintaining a P38 is challenging.

I understand you have a few other issues on your blend distribution system. Mine hasnÂ’t broken yet but Â…. If you need a hand you can contact me through here as IÂ’ve lived in Canberra since the late 70Â’s and IÂ’ve been using a Nanocom EVO as soon as I bought my P38.

At the moment IÂ’m trying to get my ABS ECU to talk to the BECM as I think the ECM thinks it is new and doesnÂ’t know the VIN of my car, which the rest of the system does. Hence ABS and TC dash warnings, but the powered brakes work as normally, so we all have to learn. Regards, Gary.

[SSchiwy]

Hi Gary, Simon Schiwy here - we have exchanged messages about my car's heavy and other issues. You mentioned you live in Canberra. I am located in Googong. If you happy to chat about the issues with my car please let me know and your mobile number. Cheers, Simon

[SSchiwy]

Good evening one and all. Since posting the issue I managed to order a refurb HEVAC from UK plus some other parts and have put the car in to an auto elect to fix the issue. Long story short the new unit has not fixed the issue. The seller said the unit was compatible with my car - last of the series in 2002. The new HEVAC unit gets more cold air out but it seems the mode actuator does not activate the selected mode fully as the gear does not move far enough to get full force of air out of the face vents. The auto elect took some videos and said the old unit moved the flaps further. The new unit still also has the book page up. Any advice gratefully received. cheers, Simon

[prelude]

The new unit (second hand) has the blend motors calibrated to the car it came from, ie. differently. You need a device that can do that for you (like a faultmate). Once that is done you can reset the fault memory and excersice the unit (ie let the tester run the flaps back and forth) to see if you get any more errors.

Cheers,
-P

[SSchiwy]

The new unit (second hand) has the blend motors calibrated to the car it came from, ie. differently. You need a device that can do that for you (like a faultmate). Once that is done you can reset the fault memory and excersice the unit (ie let the tester run the flaps back and forth) to see if you get any more errors.

Cheers,
-P
Many thanks Prelude. I will go in search of a nanocm evo fault mate!

[SSchiwy]

Many thanks Prelude

[SSchiwy]

Hi Simon,

I had to repair my HEVAC on my 2000 P38 as some sections of the screen had failed earlier. I bought the zebra part from the UK so I safely stripped the body from the back of the harness and it eventually worked, after about 4 attempts. The zebra is fragile as are the electronics, but itÂ’s doable as mine is still working after 5+ years since the repair. IÂ’m not sure but I may have bought another spare zebra, just in case - which is usual to me as the experience of maintaining a P38 is challenging.

I understand you have a few other issues on your blend distribution system. Mine hasnÂ’t broken yet but Â…. If you need a hand you can contact me through here as IÂ’ve lived in Canberra since the late 70Â’s and IÂ’ve been using a Nanocom EVO as soon as I bought my P38.

At the moment IÂ’m trying to get my ABS ECU to talk to the BECM as I think the ECM thinks it is new and doesnÂ’t know the VIN of my car, which the rest of the system does. Hence ABS and TC dash warnings, but the powered brakes work as normally, so we all have to learn. Regards, Gary.


Hi Gary, keen to take you up on your offer of using the EVO, cheers, Simon

[SSchiwy]

HI Gary, keen to take you up on your offer to use the EVO