Apologies for the long post. I’d be grateful for some help on an issue with the air con system on my 2013 L405 TDV8 autobiography, with rear air con.

Having functioned well when parked, the system stopped blowing cold air on starting the vehicle c. 10 mins later.

It was diagnosed initially as a failed compressor, which was subsequently replaced by a local Land Rover specialist. Once regassed, the new compressor clutch remained engaged permanently and the system built significant pressure before the mechanic switched off the engine.

Believing the replacement to be faulty, a further compressor was installed as a warranty item, but again the clutch remained engaged permanently.

It was then believed that the pressure sensor was faulty, which was replaced, however the issue remains.

On start up, there is cold air initially and you can feel the pipes going cold, but that stops after a few minutes as the pressure rises. The amount of gas has been verified, but they also tried removing a small amount to see if that made a difference (it didn’t).

As I needed the vehicle back, the compressor has been unplugged while the garage contacts autologic technical support for additional guidance.

I have reviewed the live data on the various system sensors via icarsoft - all temperature sensors give a reasonable value (external, cabin, various ducts and evaporator all showing close to ambient temp) and the pressure sensor gives a reading. The climate control module appears to be functioning on the remainder of the items it controls and is showing no fault codes.

The only fault code is for the windscreen mist sensor, which is also showing a constant 0% on the live values, so I assume that has failed.

Additionally, the cabin filter was pretty dirty (now replaced although compressor not plugged back in to test if it’s made a difference).

The only other potential I can think of is that the vehicle batteries are not in great shape and I gather there can be some odd issues when that is the case. (Will be replacing the batteries over the weekend).

With the fact that the system can hold pressure, combined with the instant nature of the failure, I believe the problem is electrical (I may be completely wrong on that) - are battery issues or the windscreen mist sensor likely to cause the compressor to run with the clutch permanently engaged?

Any help appreciated and thanks in advance.

Dan

I guess it’s 1234yf gas, do you know what the gas pressure are reading when in use with A/C on. The best way to measure this is with the A/C mechine coupled up to gas. Read high and low pressures with engine running and a/c on. I would expect around maybe 10 bar on high side ( rough estimate without checking data).
If this is correct then the pump can run for hours on end with out a problem. The pressure sensor if faulty would expect it to put fault code in and shut the system down if faulty ( very common on VAG cars)
The mist sensor on windscreen are common to fail on JLR cars. Again I would expect a fault code , possibly something like:

B13C2-49 (2 Front Windscreen/Windshield Misting Sensor - internal electronic failure in HVAC. But unsure if this would keep compressor in all the time , and if so the compressor should be ok to run for hours on end , just like a long journey

It'd be useful if you posted up the live stream data as that will give useful background to any would be assistants. That'd be the standing AC off info and the AC on info, pressures and temperatures. These will be similar whether the car is on a R134a or a R1234yf charge. You can also check the air flap positions are moving with the dial settings on a scanner.

Thanks for the feedback.

I don’t have the pressures, I was told it was high, but they didn’t give me a figure. I’ll find out when I next talk to them.

The error code I’m getting for the windscreen sensor is indeed B13C2 (doesn’t have the further digits on my scanner), but as you say, I’m not convinced that would make the compressor run continuously.

I’m replacing the batteries over the weekend as they are well past their best and will then get back into the garage to find out the pressures and see if it’s made any difference.

Thanks,

Dan

Pressures are only meaningful on the day as they do vary a good amount with the prevailing ambient conditions.

Understood.

I’ll get proper feedback from them on the day