Member Since: 30 Dec 2009
Location: Melton Mowbray, Leics
Posts: 181
Rear air con - not working but front is...
Hi Everyone
Yesterday was the first day where I could really tell the aircon was working in my D3 since I have owned it. It has rear air con as well, but the upper vents in the headlining were only blowing warm when the rest of the car was cold.
The vents in the rear of the centre console/arm rest were cold though.
I tried the manual controls in the roof set to ‘blue’ and then the HVAC unit set to manual for the rear rather than auto but no joy.
I’ve done quite a bit of reading and understand the rear pipes can corrode/leak etc, so my question is;
Are there any other explanations for what I have experienced, other than that the rear pipes have corroded and someone has previously blocked off/swapped out the engine bay aircon pipes to be ‘front only’ pipes and re-gassed?
Just wondered if by chance there is a way to tell under the bonnet if this is the case, or if maybe there is a blend motor or something in the rear that might not be working?
I have no fault codes from the HVAC by the way...
14th Apr 2021 7:18 am
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
On mine when under car pipes corroded the whole a/c system went down, so the fact you have no rear a/c would suggest just maybe someone has taken the cheap option and replaced the underbonnet pipes for rera a/c with front a/c set up only?
Simple enough to check with engine running and a/c on cold, lay on floor and slide your hands up under the passenger side sill and you will feel the pipes they are wrapped in foam lagging, follow them along until in line with rear of pass side back door and there is a connector which is not lagged, between air compressor and air tank if the sytem is working this connector will be cold.
Centre vents are fed from the front system, all overhead vents are the rear system.
14th Apr 2021 7:26 am
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Member Since: 30 Dec 2009
Location: Melton Mowbray, Leics
Posts: 181
lynalldiscovery wrote:
On mine when under car pipes corroded the whole a/c system went down, so the fact you have no rear a/c would suggest just maybe someone has taken the cheap option and replaced the underbonnet pipes for rera a/c with front a/c set up only?
Simple enough to check with engine running and a/c on cold, lay on floor and slide your hands up under the passenger side sill and you will feel the pipes they are wrapped in foam lagging, follow them along until in line with rear of pass side back door and there is a connector which is not lagged, between air compressor and air tank if the sytem is working this connector will be cold.
Centre vents are fed from the front system, all overhead vents are the rear system.
Thanks - sounds easy, will check. I had a look at the other thread re blanking off the rear and the pictures aren’t that clear as to what is different in the engine bay (ie to look for !). Will do a bit more digging on pictures of the two different sets of pipes for the engine bay so i can try to tell a visual difference.
14th Apr 2021 7:52 am
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
If you get stuck I can take pics of my pipework if it will help?
14th Apr 2021 4:58 pm
douglastic
Member Since: 31 May 2017
Location: SoCal
Posts: 33
Have you checked system pressure?
Either with IIDtool or at a shop?
My rear went weak when I needed a recharge (was only 25%!)
After, all was well.Doug
2007 LR3 HSE - Chawton/Alpaca - SoCal
14th Apr 2021 5:31 pm
itguy
Member Since: 30 Dec 2009
Location: Melton Mowbray, Leics
Posts: 181
lynalldiscovery wrote:
If you get stuck I can take pics of my pipework if it will help?
Thanks, let me have a look at mine today and see if there is anything obvious first, then that might help
15th Apr 2021 6:58 am
itguy
Member Since: 30 Dec 2009
Location: Melton Mowbray, Leics
Posts: 181
douglastic wrote:
Have you checked system pressure?
Either with IIDtool or at a shop?
My rear went weak when I needed a recharge (was only 25%!)
After, all was well.
I have done, yes, but only to check it actually had pressure, which it did. Do you know what system pressure I should be aiming for? Mine varied when I checked it, presumably due to the variable nature of what level of cooling demand on the AC compressor it wanted, so do you put the system in it full cold to test (maybe?)?
15th Apr 2021 6:59 am
itguy
Member Since: 30 Dec 2009
Location: Melton Mowbray, Leics
Posts: 181
Well, mystery solved.
There must have been a leak in one of the rear pipes, so at some point in the cars history it has had the front pipes changed to make it ‘front only’ as a system.
I can tell this won’t sit well with my OCD wanting the car to operate as intended.... but is it REALLY worth it to start down this rabbit hole.. I suspect wait until the body needs to come off for something else, then replace all the mid and rear pipes at the same time.
15th Apr 2021 10:25 am
LT
Member Since: 31 Dec 2005
Location: South West
Posts: 23391
Have an independent air con specialist replace the rusty rear a/c pipes with plastic ones. 2006 D3 HSE (Original & still the best)-GONE
2010 D4 HSE (A bit bling)-GONE
2014 D4 HSE (Almost too bling)-GONE
2015 D4 HSE (A heated what?)-GONE
2016 D4 Landmark (Written Off)-GONE
2016 D4 Landmark (Surely the last!) PD1881 rims-GONE
2017 FFRR SDV8 Autobiography
15th Apr 2021 10:33 am
itguy
Member Since: 30 Dec 2009
Location: Melton Mowbray, Leics
Posts: 181
Is this possible without body off?
I do know a good local aircon chap that I have always used before, but not sure if he does this or not..
15th Apr 2021 10:35 am
Bungle
Member Since: 07 Apr 2015
Location: Wanborough
Posts: 254
You can change the pipes without taking the body off but it isn't an easy job (mine was worse as I have a fixed LPG tank where the spare wheel is which makes the access even harder). I spent two summers driving around with my wife and small child in the back and they definitely appreciated it, especially as mine has the "greenhouse" glass roof in the back. It really depends on how much you use the back seats.
15th Apr 2021 12:43 pm
LT
Member Since: 31 Dec 2005
Location: South West
Posts: 23391
itguy wrote:
Is this possible without body off?
I do know a good local aircon chap that I have always used before, but not sure if he does this or not..
Yes and plastic piping easier to fit as well. Not that it’s an easy job. No point replacing like with like. It will just rust out again.2006 D3 HSE (Original & still the best)-GONE
2010 D4 HSE (A bit bling)-GONE
2014 D4 HSE (Almost too bling)-GONE
2015 D4 HSE (A heated what?)-GONE
2016 D4 Landmark (Written Off)-GONE
2016 D4 Landmark (Surely the last!) PD1881 rims-GONE
2017 FFRR SDV8 Autobiography
15th Apr 2021 12:46 pm
DWDG
Member Since: 27 Jul 2020
Location: Bedford
Posts: 101
My local (non LR) garage didn't know that the rear AC models need more coolant (810g of coolant) than the non-rear AC models. I think that's why last year it was fairly weak as they didn't check and went with the lower amount.
When I took the previous one to Kwik Fit it was the first thing the guy asked me: does it have rear AC?
When blocking the rear AC pipes do you still need the full volume of coolant or will the smaller amount suffice? I'm sure it won't matter if they just go all guns blazing for the larger amount until it just get full but I'm no expert but considering having mine changed now rather than blocked off as there is a slow small leak.2007 Discovery 3 HSE Lugano Teal
2011 BMW 520d Touring Sophisticato Grey
2000 Porsche Boxster 2.7 Arena Red
2002 Porsche 911 3.6 C4 Cabriolet Artic Silver - sold last year
1987 Porsche 944S Black - sold last year
2006 Discovery 3 HSE Buckingham Blue - sold last year
2012 Ford Grand CMax Panther Black (wife’s) wish we’d sold that instead!
17th May 2021 2:41 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
The amount of gas/oil is quite important, so if you blank the rear off you only need the smaller amount of gas.
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