Just pondering really. A friend has a 2001 bordoux although it's not spelt like that I don't think. Mine is dhse so has heated seats, leccy seats, heated front windscreen etc. His has non of this and never has but his hvac has all the buttons for these features same as mine. Would LR fit the same panel regardless? Or his is a replacement from a breaker because the original failed?

If he doesn't have heated seats or windscreen, then it has been changed. There are different versions of the HEVAC that either have all the buttons or only the ones a particular car has. The buttons appear to still be there but don't have the markings on them to show what they do and are just blanks that don't do anything. The Bordeaux is a bit of a weird one. People think it is a luxury version but it is actually a near base model with red paintwork, red carpets and red piping on the seats. No heated screen, headlamp wash/wipe, no High Line sterero, no electric seats, etc so your DHSE will be a much higher spec (same as a petrol HSE).

I was pondering mainly because his AC doesn't work, kwikfit gassed it last year but no cold. I had a little play with limited knowledge and his clutch pulls in when directly energised , relay swopped, no difference. It was last year when I did this so I'm unsure of what I actually did but I ' think' there was no power to the relay but unsure now, bloody memory!
I wonder, think I've read somewhere too, that earlier hvac isn't compatible to late hvac in relation to AC ?? His car is 2001.
If I get to fiddle again , is there a flow chart for AC I could follow, got dmm and nano but a bit wet behind the ears if it gets too techy.
I think romanrob did something on landyzone but I can't find it.

My AC works great BTW after fitting the earlier condensor replacing my unobtainable later one, never had a car with AC before and its bloody lovely especially as I don't cope well in the heat.

It may just be low on refrigerant, particularly if Kwikfit did it. The P38 takes a lot of R134a, 1250 grams in a GEMS and 1380 grams in a Thor but unless the muppet that did it programmed the machine properly (which most don't as they don't know how), it will have put the default of 800 grams in. When low it will work but not well and the pressure will drop as the ambient temperature gets warmer so it won't work at all when you actually want it to. If it wasn't fully charged in the first place, even the smallest leak will cause the level to drop below that were it will work at all. Simplest check is to very briefly poke one of the Schrader valves and see if there is any pressure there. Admittedly you are committing a criminal offence by intentionally releasing an ozone depleting substance into the atmosphere but if you've got a leak you've been doing that anyway (but not intentionally).....

The signal from the HEVAC goes via the dreaded connector behind the RH kick panel. On a GEMS it drives the compressor clutch directly via the pressure switch so the HEVAC can detect the amount of current being drawn and bring the book on if it doesn't see sufficient draw. On a Thor the HEVAC drives the relay which sends power, again via the pressure switch, to the compressor clutch. In this case a later HEVAC won't bring the book on as it is only supplying a low current to drive a relay and not the clutch directly. So a late HEVAC will work on an early car but not the other way round. If he does have an early HEVAC, then it will have the book showing as it is expecting to see lots of current being drawn but there isn't. As soon as that happens it takes the power off that output and doesn't try to engage it again. If the book is showing, poke the AC OFF button and see if the book is still there on the next restart. An early HEVAC won't detect the problem if it doesn't try to engage the compressor clutch, so won't bring the book on. If Nanocom shows a compressor clutch fault, then it is an early HEVAC.

If you have power to the relay and pressure in the system, put the temperature on Lo on both sides. If the relay doesn't click in, then look at the kickwell connector, if it does, then it might be a bad connection at the pressure switch (mine had one when I first got it and a P38 on a hot day with no AC is not a pleasant place to be). Unplug that and give it a squirt of contact cleaner. If it still doesn't work, put a wire jumper between the Green/White and White/Light Green wires on the pressure switch plug, that will simulate an acceptable working pressure in the system (between 35 and 305 psi). If the clutch kicks in then, either the pressure is below 35 psi or it is low on refrigerant.

One other thing to check is the compressor clutch air gap. It should be between 16 and 30 thou between the clutch plate face and the pulley. A quick check for that is to tap the clutch plate with the handle of a screwdriver while it is trying to operate. If it clicks in then and stays in, the the air gap is likely too large and the system isn't supplying enough current to pull it in but once in, it will stay in. However, my bet would be low or no refrigerant

Cheers Richard. I will investigate further when I can pin him down.

I have read somewhere that the early version HEVAC control heads that have the outdoor ambient air temp sensor located in the fresh air intake plenum versus the later units which had that sensor located in the front grill area are somehow different? Maybe how the temperature offset is calculated?
Can anyone verify this?

You are right that the sensor location was moved but I don't think it will have required any difference to the HEVAC. The main problem with the earlier ones is that with the sensor located where it is, it will read much higher than ambient initially if the car has been parked after the engine has been run as it is right next to the engine bay.

The only difference to the later HEVAC with regard to temp sensor is that it will hold the last value of the external temp until it's detected road speed for more than 10s.

This was added when they moved the sensor to ensure there was fresh air without latent heat from the radiator etc (because of where the sensor ended up being mounted) before the HEVAC used the reading. If you've had the HEVAC disconnected and powered on, or the sensor disconnected etc then you sometimes will see -40 on the external temp until it's had a chance to update. Other than that, the sensors are the same and the only other main update to the HEVAC was the compressor clutch fault being changed, so it wouldn't trigger with the wiring update where it drove a relay to power the compressor clutch, rather than direct from the HEVAC itself (which wasn't powerful enough - especially as the clutch gets older/wears/requires more current to activate).