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Discussion Starter #1
Was 10 degrees out today, neither the drives or passengers worked... Later in the day the passenger's worked but the drivers the fan would start, then shut off... Just now the drivers side ran for a few minutes then just stopped. Wondering if these have an air filter or are easily checked/replaced...

TIA

~Brad
 

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There is a filter on each one, and easy to replace on the seat portion, a little more involved on the back portion.

Does it happen on both heat/cool? Does it happen when just back is selected?

There were a few issues with the thermistor in the assembly that would cause it to think it was overheating, and make it shut off shortly after being turned on, but this can easily be an airflow issue as well. Don't have the PN for the filter on hand, but by the book should be changed every 30k miles/2 years(for the +10 L322, not in the book for the 07-09, but the same system)
 

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Discussion Starter #3
There is a filter on each one, and easy to replace on the seat portion, a little more involved on the back portion.

Does it happen on both heat/cool? Does it happen when just back is selected?

There were a few issues with the thermistor in the assembly that would cause it to think it was overheating, and make it shut off shortly after being turned on, but this can easily be an airflow issue as well. Don't have the PN for the filter on hand, but by the book should be changed every 30k miles/2 years(for the +10 L322, not in the book for the 07-09, but the same system)
Thanks for your posting as usual :)

Looks like it's a real problem for me... It happens no matter what at this point. This morning it ran for about a minute then shut off... Then nothing. Next attempt hours later it turned on for a second then shut right off.

How hard is to to swap out the filter? Might just try that and see what's what... I'm sure they've never been changed. I don't see a procedure in rav
 

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Funny, I just had the exact same thing happen to me... very cold out. Drivers side heated seat mode is illuminated, but it never gets warm. Passenger side appears to work. Cool mode works on both sides, I can feel the air flowing.

For the heat, is that still via forced air? or is there a heating element? I see it looks link there was a TSB at some point for materials inside the seat obstructing the fan. I may have to take a look inside and see what I can see but not sure when I'll have time.
 

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The bulletin is solely for the backrest portion, and a noise.

It heat/cools by use of a Peltier Cell, so same element for hot and cold, however, the heating portion of it puts the unit in a closed loop mode that relies on the thermistor, where as cool is open loop, and the thermistor feedback is solely for fault finding and ice prevention. No standard heating element in the seat.

I have had several with bad thermistors that cause the heat to not work, but when that happens, the fan shuts down too. I suppose it is possible for the thermistor to send back a reading of 'hot enough' but not 'overheat' and the fan to still function just without voltage to the cell.

With cold working, you can assume that air flow past the element(to cool both sides of the cell), and wiring(same for hot and cold, just reversed polarity) are in tact. There is a control module, but I haven't seen one replaced yet.

The filter on the seat bottom is straight forward, but somewhat tight, it just pops on the outside of the fan, which is under the seat. The backrest filter requires removal of the lower rear seat cover for access.
 

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Interesting... are these thermistors integrated into an expensive part, or is it something that can be replaced separately, or desoldered and replaced maybe depending on how intricate the design is? I'm pretty sure generic ones could be found for a few dollars.

I just went out and listened very carefully, and what actually happens is, as soon as I switch it to heat, the fan comes on, and then it shuts off a few seconds later... the lights remain illuminated on the dial on the console. Also, once this happens it will not blow cold air either, I have to shut it off and restart before it will blow cold air, but then as soon as I try hot, it stops working. Seems like this could be a bad thermistor.
 

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Oh, interesting... just hooked up the iid tool and it is throwing up a fault code relating to the "peltier cell" which sounds a lot like the thermistor you are referring to (the thermistor probably built in)? The code does not come up if I do not select heat, perhaps because it is unmonitored in the open loop?

In theory, this system looks a lot more robust than a "normal" heating element... you can use one cell either absorb or release heat depending on the direction of the current. I like the idea at least.
 

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Yeah, the Peltier cell setup is pretty neat, unfortunately not efficient enough for most applications. LR actually had a pre-prod truck years ago with a full Peltier HVAC system, instant heat on cold days, instant 'AC' on hot days, it was cool, but a huge strain on the electrical system, and until they can make ones that are anywhere close to as efficient as change of state AC it won't be in any cars in the near future(Peltier cells are ~5-10% vs standard AC at ~40%)

Anyway, yeah, the thermistor is somewhat built in, but not really integrated. It comes as an assembly, but I'm sure something could be wired up easily. I have one at work that I can see if there are any sort of markings on the thermistor for reference. Testing mine won't help, as it was removed for the same failure, but I kept the part, as I use these to help cool my work computer(used to work in a shop without AC, as it got hot back inside my toolbox behind my monitor, and I didn't feel like investing in a real cooling system)

As far as robust, I agree, I have yet to see one fail due to a cell failure, always mechanical fan issue, or thermistor issue. If the iid took gives you a fault number, B code, post it here, as LR had big issues with mis-diagnosed parts returned under warranty, and there is an internal document that breaks everything down.
 

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Discussion Starter #9
Good info in here so far... I replaced the filters under the seat today (easy). Unfortunately restricted air flow isn't my problem. Now 100% of the time when you turn on the car, then try to run the fan (both drivers side/passenger) fan comes on then shuts right off. The seat back fan doesn't seem to work either... Also they don't come on when you run them in AC mode. They were working last week, I find it strange both sides failed like this on the same day. The only thing I've done is pulled the battery while cleaning my MAF... Seems they stopped working pretty much right after that :whoknows:

I don't hear any grinding or strange noises when they're running either, they just come on for a second as normal, then just power down almost like they're programmed to do so.
 

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Hooked up the diagnostic again, and now it shows the fault all the time (perhaps because it is stored, I could probably clear it and see the same behavior as before)... seats still working in cool mode though, just not heat on the drivers side. Unfortunately, the IID tool does not display the B code because it has a description, it probably would only show the raw code for unknown faults... but based on the text description it looks like it probably corresponds with B1229 when I look up the text in google.

EDIT: tried clearing it and it comes back immediately... but clearing it does have the effect of allowing cooling mode to work again without actually having to restart.

EDIT AGAIN: searching through the service manual, I found the B codes for the HVAC module and B1229 is not one of them... so google must have returned something for a different vehicle. From looking at the various DTC in the manual, I cannot tell which one it would be referring to. Perhaps I'll ask GAP if they have a way to display the actual code associated with the message.
 

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Discussion Starter #11
Hooked up the diagnostic again, and now it shows the fault all the time (perhaps because it is stored, I could probably clear it and see the same behavior as before)... seats still working in cool mode though, just not heat on the drivers side. Unfortunately, the IID tool does not display the B code because it has a description, it probably would only show the raw code for unknown faults... but based on the text description it looks like it probably corresponds with B1229 when I look up the text in google.

EDIT: tried clearing it and it comes back immediately... but clearing it does have the effect of allowing cooling mode to work again without actually having to restart.

EDIT AGAIN: searching through the service manual, I found the B codes for the HVAC module and B1229 is not one of them... so google must have returned something for a different vehicle. From looking at the various DTC in the manual, I cannot tell which one it would be referring to. Perhaps I'll ask GAP if they have a way to display the actual code associated with the message.
Yikes... lame problems for us! Have you noticed we're the same person or is that just me? Hahah

This morning mine wouldn't start, dead battery (orginal so it was due). Figured there was a chance since the battery was fouled up perhaps the heated/cooled seat computer was seeing a flux and shuts them down. No dice... Turn them on, they run for a moment then just shut off. It's the same for both drivers and passenger. They run for a moment perfect then shut off as if it's in their programming. They behave the same way no matter what setting they're on. It has to be something drivers/passenger is tied into, because they both started acting up at the same time. Also once each has run for a moment and shut down, neither will run at all until the car is restarted.
 

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Discussion Starter #12
Okay after some reading I think I have it figured out, all the seat fans work except the one in the back rest of the drivers seat... According to the shop manual if one fails they're all instructed to shut down. The shop manual doesn't tell you how to remove the fan though. I suppose the fix is to remove the fan, replace, then they should all work... Unless somehow the plug is fouled... The manual isn't too detailed in the operation/layout/removal of these things.
 

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My driver's side hasn't worked for awhile. My driver's seat will briefly blow (either on hot or cold setting) then immediately shut down.

Dealership told me (with their usual specificity...) the unit was damaged (cracked housing?) when I moved the seat back into whatever was in the rear passenger footwell behind the driver's seat and kept going until the interior of the seat's air/heat unit cracked/was damaged. The biggest problem I have with their explanation is I've never moved the seat back into anything that was on the floor behind it that I am aware of...



It's been touched on a couple of times...
http://www.rangerovers.net/forum/6-range-rover-mark-iii-l322/12014-ventilated-seat-issues.html
http://www.rangerovers.net/forum/6-...-2007-rr-supercharged-heated-cooled-seat.html
 

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Discussion Starter #14
My driver's side hasn't worked for awhile. My driver's seat will briefly blow (either on hot or cold setting) then immediately shut down.

Dealership told me (with their usual specificity...) the unit was damaged (cracked housing?) when I moved the seat back into whatever was in the rear passenger footwell behind the driver's seat and kept going until the interior of the seat's air/heat unit cracked/was damaged. The biggest problem I have with their explanation is I've never moved the seat back into anything that was on the floor behind it that I am aware of...



It's been touched on a couple of times...
http://www.rangerovers.net/forum/6-range-rover-mark-iii-l322/12014-ventilated-seat-issues.html
http://www.rangerovers.net/forum/6-...-2007-rr-supercharged-heated-cooled-seat.html
Does the passenger side work? If so I'd be totally confused by my situation now. As far as I can tell the drivers side back rest doesn't turn on... all the other seat fan turn on but then immediately shut off. This is a stupid problem to have and really painful in freezing temps :(
 

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Yeah, hehe, I guess as it turns out the '07 can still have a few gremlins as well as the earlier BMW units... but at least I haven't had any coolant, PCV, or other engine issues which would be much larger show stoppers than heated seats. (On a side note we recently traded my wife's BMW 325 for a Lexus hybrid SUV and she is now taunting me because her heated seats are working just fine! I bet her we would end up having a similar number of problems with both vehicles over time, but this is not a good start.)

I just heard back from GAP (fantastic customer service) and they said these DTC "B" codes in the service manual are on ECU’s which are on the CAN network and follow the standards. The HVAC on the other hand is not following these standards (BMW did not implement this). So... perhaps the dealer diagnostics have some other way of translating things.

Based on the fact that everything works except the heat, it does seem likely to be a problem with the thermistor. I will find it and compare the resistance to my passenger side which is still working.
 

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Discussion Starter #16
Yeah, hehe, I guess as it turns out the '07 can still have a few gremlins as well as the earlier BMW units... but at least I haven't had any coolant, PCV, or other engine issues which would be much larger show stoppers than heated seats. (On a side note we recently traded my wife's BMW 325 for a Lexus hybrid SUV and she is now taunting me because her heated seats are working just fine! I bet her we would end up having a similar number of problems with both vehicles over time, but this is not a good start.)

I just heard back from GAP (fantastic customer service) and they said these DTC "B" codes in the service manual are on ECU’s which are on the CAN network and follow the standards. The HVAC on the other hand is not following these standards (BMW did not implement this). So... perhaps the dealer diagnostics have some other way of translating things.

Based on the fact that everything works except the heat, it does seem likely to be a problem with the thermistor. I will find it and compare the resistance to my passenger side which is still working.
Well good luck getting it going and keep us posted... If someone knows exactly why both front seats would operate for only a moment before shutting off please let us know as I'd love to remedy this problem sooner than later `8)
 

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Discussion Starter #17
Been messing with this way too much today LOL... So I pulled the POS/NEG off the battery and did the whole touching them together to clear ECU's trick. Now all of the seat fans work where previously the drivers seat back did not... I'm also able to run it without issue on cooling mode... As far as heating it turns on for a moment, then right off both drivers side and passenger... Both worked flawlessly a few days ago, seems like whatever control module is in charge of the heated/cooled seats is thinking they're overheating and shutting them down. Or the low temps damaged the thermistor (not sure where that is or how many there are).

I pulled this from the manual
The climatic seat control module monitors seat heating through a NTC temperature sensor. The temperature sensor is only used to monitor seat heating. Seat cooling is open loop, with no temperature signal provided back to the control module. When a temperature selection is made through either of the rotary controllers, the instrument panel switch pack provides a PWM signal to the climatic seat control module, which interprets the PWM signal as a temperature value and attempts to heat or cool the seat accordingly.

I carry NTC sensors for work (aquarium industry) use them to pull water temp to send to a controller to actuate heaters. They fail all the time if they're left in extreme cold/of age/moisture... How many are there and where are they located? Unfortunately the rover manual mentions them, but not in any sort of detail.
 

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The NTC sensor *is* the thermistor, I assume one in each seat as part of the Peltier cell... NTC == negative temperature coefficient resistor... aka thermistor. Their resistance changes significantly with temperature changes, they are usually a ceramic or polymer material, as opposed to more "normal" sensors that are made of metal.

You are correct that they do not like water... also they tend to be sensitive to excessive current flow, they can easily be damaged this way. I would think the control unit should control the current properly but who knows... perhaps some further probing will be necessary. I may need to take stuff apart to get at it. Looks like I have to take the back of the seat apart somehow according to the manual. It doesn't provide the greatest instructions, but I'll probably be able to figure it out (not tonight though, and perhaps not until at least the weekend).
 

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The Climate Controlled Seat Module is on the MS Can, and does very much have B codes, but anyway, the B1229-13 is a valid code, and corresponds with your failure, details as "Left Seat Back Temperature Sensor - Circuit Open". I don't have Acrobat Pro on my computer here, and printing that section of the faults isn't pulling all the letters for some reason, but there isn't much information there to begin with.

Checking resistance of the thermistors is pretty easy, as they all feed back to the CCSM, under the drivers seat, see attached pinout.

I was wrong in thinking the thermistor wasn't integrated, it wires up into the Peltier cell, green wires in picture are for thermistor, blue and yellow are Peltier power/ground. There are a few pinch points right at the housing, but since the wiring is part of the unit, LR is a replace not repair policy on this, so I've never gone further then a simple ohm check on it.

IMAG0187.jpg
IMAG0188.jpg


As to both happening at the same time, this is odd, and I don't suspect a module failure, never replaced one, and don't know of any issues with them, but let me look into it a little.
 

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...both seats not working on heat.

Long shot, as I would expect other issues too, but has it been cold enough for you to use(and see if functioning correctly) the heated front screen?

Past that, I would try maybe warming up the interior for a while, as to maybe warm the thermistors up past the point they are now, then cycle the key, and see id the heat will work then. Also, is this happening when just seat back is selected on both seats?
 
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