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Apr 23 2019
24 April 2019 - 22:42

98 GEMS
So O rings done, I've now got full cabin heat, but the UK weather just went tropical (for a few days, anyway), so now I need the AC... Last summer the AC worked, after I replaced the condenser and added a 2nd hand drier.

This year the AC is not playing. The compressor works, when I give 12v and and earth direct to the connector (C166P) the clutch engages, and the cabin chills as expected. In normal use though nanocom says AC grant "no", but as far as I'm aware the nanocom doesn't also tell me the AC request status - if I could find that in the nanocom menu somewhere it could help with diagnosis, and if I could force it on that would be even better. I also need to disconnect the BECM diagnostic connector as it apparently interferes with the Nanocom's interrogation of the HEVAC ECU - I haven't done that yet - but I don't know if that wd screw up the readings or not.

It crossed my mind that one of the many sensors may be feeding in rubbish data to the HEVAC ECU.
I got ambient 12.7 (fine)
aspirator 18.2 (fine)
evaporator 16.2 (ok, just replaced with a 2nd hand one off a freelander, but same Valeo part number)
heater core temp -0.20 (although it climbs once I've turned up to Hi)

Is the heater core temp way off - seems so. What range should it read in? If that were the case is that going to explain why the AC is not being requested? I recently did the o rings so cd have disturbed something on the sensor

In general any HEVAC faults I have had in the last year are clearable. I have a rare "compressor open circuit" message (but I had that last year too, when the AC was working) and the right blend motor needs fixing at some point. I have a periodic service book come up, but I think it's usually triggered by me asking the jammed blend motor to move (ie by pressing the "wrong" button to adjust the air vent flow)

Seems my first job is to get to air con grant "yes" and then I can start testing stuff... And maybe pressure test the aircon system

25 April 2019 - 00:26

Just read Rutland's post about wiggling the heater core sensor, I'll give that a go too

25 April 2019 - 20:37

Thanks guys, I was being lazy and trying to avoid pulling the cheeks off and HEVAC out for the millionth time :o) but that may be next step... This eve i disconnected the evap sensor - open circuit goes to -40 bridging the connectors defaults to +80 - neither reading is much good to me, so I plugged it back in.

The heater core sensor was wiggled, no change, reads about 0, despite the pipe being too hot to touch. Unplugged and the "reading" is -20, when I bridge the contacts on the plug the default setting goes to +80. I figure that latter reading more closely reflects what the heater core temp would read when the vehicle is running, so I'll drive with the bridge in for a few days and see if the AC settles and kicks in. Sounds like the heater core sensor is mis-reading, but equally I'm not sure that replacing it is going to solve the no air con situation.

At 12V the clutch is definitely working, and immediately chills the cabin, so after I get an air con grant Ican definitely check the voltage drop (if any), I already checked the earth point for the condenser ground wire, and no probs. Last summer (ie after I bought it) the clutch wasn't working, so I removed it, wiped some of the crud off and it started working again, so gap seems ok, if marginal

Tomorrow I'll send 12V to the input side of the trinary switch and confirm that is functioning ok given that there seems to be sufficient pressure in the air con for cooling. And then I'll pull the HEVAC unit and see what I have on the request/ grant wires

Assuming I have air con request, but no grant, then that means some other condition is not being met at the ECM- has anyone stumbled across a list of what those are?

26 April 2019 - 22:27

Thanks guys. I'll check out those connectors too

30 April 2019 - 09:53

Thanks Marty, no amount of "wiggling" has got my heater core sensor responding properly. I may try removing / reinstalling next. Is it relatively easy to desolder the thermistor and replace a new one, do you think?

Rgds, Rob

30 April 2019 - 21:32

I don't have a thermistor, but I had a jumper across the plug the last few days to see if the system might be tricked into thinking it was a balmy plus 80 and time to put the air con on, but no dice. So I'm not convinced it's the sensor. Am a bit behind plan on the A/C diagnostics as I was doing a Defender oil and coolant change over the weekend, and the weather got cold again :o)

30 April 2019 - 20:33

To answer my own question, no, it's a sealed unit

07 May 2019 - 12:44

Pretty sure my heater core sensor is not good (so don't use this data as a reference), but after chucking the sensor in the freezer it reads about 700k ohms. At body temp it's about 230k ohms, over a kettle it's about 45k. On Nano it was reading about zero at rest, and 20 degrees or so when up and running, so definitely out of range. Anyone got real data from a working one?

08 May 2019 - 08:43

I got a 20k NTC thermistor, arrived yesterday, plugged it in, and Nanocom reads more sensibly. It didn't do anything for the air con though... I'll get a replacement sensor and go from there. At least the weather is s*** these days so no need for air con, although on the plus side I got my sun roof working the other day (was turned off in the BECM...if only everything was that easy).

08 May 2019 - 10:17

Thanks, yes I forgot to mention the O2 sensors, I had a look in that part of nano the other day and nothing leapt out, but I'll have another look, now that I know what I'm looking for, tnx for the advice

08 May 2019 - 08:55

GEMS 4.6

Engine is perfectly driveable, perhaps a bit of a tappet-like rattle on one cylinder, but notably smelly at idle... I don't have a nose for these things, but it smells a bit rich... Does that mean the cats are up s*** creek (distinctly possible, but sounds expensive), or the MAFs playing up (i haven't removed it/ cleaned it at this point) ? HT leads and plugs are new. All the old plugs looked good on removal too. LH head gasket recently replaced. All injectors resistance tested consistently (although high end of expected range).

Any thoughts from our experts?

Rgds, Rob

09 May 2019 - 22:12

I fitted Monroe front and rear in the last six months, which seem fine. That said, after reading your post Clive i now think I am not discerning enough - I only have a Defender's coils (Terrafirma shocks) to compare to, so I would put up with anything, and the old shocks i took off the P38 were toast.

14 May 2019 - 13:51

Hi guys,

Any recommendations for a good/ sensibly priced tracking alignment garage in SW London. Two different guys are wanting to charge me c£150 to do it...which seems a bit of a p*** take. Or should I just invest in the ebay laser kit that's showing up on the "uneven tyre wear" thread?

14 May 2019 - 21:02

there's loads of Formula 1s, but unfortunately a bit sparse around SW London. ATS said £60, and it's close, so I may just go with that. How much did the LR dealer charge Rutland?

15 May 2019 - 22:18

I think O2 sensors look ok? No fault codes

Bank 1
CL. USE O2
pre cat sensor hops around 0-5v (should it hop, or be steady)
LT fuel trim 0 (just cleared it)
ST trim -3.75

Bank 2
CL.USE O2
precat sensor 1.79
LT trim 0
ST trim +3.75

elsewhere:
O2 config is 11
pre cat sensor heater is reading 1.12

16 May 2019 - 08:51

Took it to ATS - they read the fronts as 0 degrees 5 minutes toe out, tie rod seized so we couldn't tweak the toe. They didn't charge - can't say fairer than that !! The rears are 0 degrees 15 minutes toe out, and I guess those should be parallel, but the rears are unadjustable so.... nothing can be done for that, right?

16 May 2019 - 10:29

After changing the rear diff on mine off I'm pretty sure that the steel bolt goes right through the rubber bush.... http://new.lrcat.com/#!/1234/87921/88041/6925 But if it doesn't then what you say makes sense

15 May 2019 - 21:21

But the wire cage wouldn't stop the nut falling off, i think it's a bit of a superfluous design- right up there with putting two ends of a wire around the diff dampers mounted on the same bolt and expecting that to stop the damper from falling off

15 May 2019 - 22:54

Circling back to air con after covering off radius arms and panhard rods, and clearing a short on my electric seats.

I have put a 22k thermistor across the terminals for the heater core sensor, concluded the old one was scrap, replacement on the way. There's a corner of Nano in the GEMS ECU mode, which records the air con request from HEVAC ( I have a yes) and in the outputs section I can in theory force the grant to yes/ no...I just haven't got that function to work for me yet - but if there's something else interfering down-stream then I wouldn't necessarily see the clutch engage - next stop trinary switch and then I guess I'll get a pressure test on the a/c line and refill if necessary

17 May 2019 - 12:04

If only it were that easy... but no, no faults...for good measure I did hit Clear Faults a few times regardless, but nothing. I also pressed the up/down selector on the dashboard a few times and at certain points it seemed to move a bit,and at one point came up v slowly to standard height. But the default setting is access light lit, standard light flashing. Is this sounding like a compressor rebuild?