April 2020-manufactured Octavia Scout 2.0TDI (MkIII facelift).

Is there an indicator in the infotainment system, or which can be read with an OBDEleven, to check the AC cooland level/ system function?

I was driving in the crazy southern European heat a few days ago and there were times when it felt like the system wasn't cooling quite as well as it usually would/ used to.

The engine temperature was always fixed at 90° (after the initial very few minutes heating up); engine RPMs were in the usual 1800-2200 range (gear S7, driving at between 100km/hr - 120km/hr), no extraordinary hill-climbing.

The moments when it felt that the system wasn't cooling as well as I'd like, I tried lowering the cabin set temperature, which didn't seem to improve the air coming from the vents. The amount of airflow seemed consistent with the fan speed dial setting. And it didn't seem to relate to the current heat load (e.g. it sometimes happened when I happened to be in shadow or going through a long tunnel, not always in an open part of the road in full sun).

thanks,

There is no dash indication for AC refrigerant level, you have to use a diagnostic tool to check the pressures before and after the compressor with the AC on.

Thank you, @PetrolDave .

On 13/07/2026 at 11:09, PetrolDave said:

There is no dash indication for AC refrigerant level, you have to use a diagnostic tool to check the pressures before and after the compressor with the AC on.

Coming back to this, when I initially read @PetrolDave 's response, I (mis?)understood "a diagnostic tool" to mean something specific to the high-pressure gas system, but, did you mean an OBD-II reader e.g. the OBDeleven that I own?

I asked Google the question of whether modern cars actively monitor A/C system gas charge/pressure, etc, and came up with:

https://autoacrepair1.com/how-can-i-check-my-cars-air-conditioning-systems-freon-level-without-opening-the-hood/

.. which comments:

"You cannot accurately confirm your car’s exact refrigerant charge without accessing the A/C system with proper service equipment. An OBD-II scanner may show A/C pressure-sensor data, compressor commands, clutch status, evaporator temperature, and diagnostic trouble codes, but these readings only provide diagnostic clues. They do not directly measure how much refrigerant is inside the system."

I'm aware that the OBDII information includes 08 - Air Conditioning, but what I haven't found is how complete is the monitoring done by the Octavia III (Facelift), in the sense of "Occasionally spending the time to have an OBDII device read the A/C control unit is actually likely to help you notice an impending A/C problem before you notice that the system isn't cooling properly"?

Any thoughts?

thanks,

You can read AC system pressure with OBD eleven, I did it last week to confirm I have a partially depleted system.

Doing this will only be a first look at the system especially while it is running under load, you should be able to check for typical running (high side) pressure for the fridge gas in your system, online - ambient temperature dependent.

Thank you, @rum4mo and @CianKT ; I'll take the car out some time in the next days to where I can park it, running, warmed up (easy in the Mediterranean heat!!), with the A/C running for a while, and plug in my OBDelevent.

rum4mo, I apologize, I don't quite understand - what does the "online - ambient temperature dependent" mean?

cheers,

-Jay

8 hours ago, rum4mo said:

Doing this will only be a first look at the system especially while it is running under load, you should be able to check for typical running (high side) pressure for the fridge gas in your system, online - ambient temperature dependent.

I probably meant using Google etc to answer the question "what is normal high side pressure in a car AC system?" - or similar, the cruel thing is, someone probably on briskoda.net has quoted expected high side and low side running pressures - but I've forgotten where I read that. You need to know which fridge gas is used in your, ie R-134A or the later fridge gas R-1234yf , a label under the bonnet will tell you which gas is used.

Edit:- for example what is the high side and low side running pressures for a car ac system - Google Search

Edited 3 August3 Aug by rum4mo

Thanks @rum4mo , I believe my car uses the newer R-1234yf (I just had the system re-charged -- it had been struggling to cool at times, just barely noticeable; I think I recall overhearing the mechanic comment on the gas version; it was in fact approximately half down on the gas charge -- remarkable that it was still cooling almost-always mostly-well at that, against 40°C outdoor temperatures for hours on open-to-full-sun French Autoroutes at 130km/hr! ).

I found some ambient temperature - gas - pressure ranges numbers online against which to compare.

My one concern is about being actually driving while having the OBDeleven app talking with my OBDeleven (Bluetooth-connected) sensor (1st generation OBDeleven device) scanning, because I've noticed that some car systems/ control units seem to react to the fact of being scanned, and I don't want something critical to driving to suddenly be affected by the scan.

Any experience, scanning with an OBDeleven (Gen 1), while driving (an Octavia III Facelift, 2017-2020 model, Diesel 2.0DSG-7)?

My fallback is to drive a bit (making the engine work, in the sun, with the A/C on), park at the edge of a fuel station, and immediately start the OBDeleven scan.

thanks,

I'd think stopping after you have been running the car and the AC for a short period in time, and connect-run your scan tool, then restart the car+AC will give you the answers that you need to know, just record ambient temperature and AC running pressure while "asking for more cooling" - then keep that info for when you check again maybe at lower temperatures so that you have a range of ambient temperatures and AC system running pressure "while working under load" - and use that for the future to access your AC's current health.

I realised after I had posted that you did give the date of build of your car, so guessed that it would be R-1234yf - but just left what I had written "as is" while adding R-1234yf as the option to R-134A.

I finally had time to drive out a few minutes and find a place to stop the car (from Barcelona city you'd be surprised how difficult that can be).

My OBDeleven original-generation dongle and app don't consistently show "live data", or maybe it's really live and the car computer only reports certain fields at specific moment? .. but it was very difficult to capture readings for a bunch of the possible data points. e.g. "A/C clutch": "Function cancelled, marginal conditions have not been met", and "Lots of different data fields, at least intermittently": "Not available" (but then, many fields, would intermittently show some data, then switch back to "Not available").

Is this a glitch, or just a known functional limitation, of OBD11/ an older OBD-II Bluetooth dongle?

That said, I got some fields:

"Coolant temperature": 88°C (although that seems to be more likely the engine than something specific to the A/C?)

Blower voltage, actual value: 6.1 V

Blower current, 4.50 A

Compressor current, actual value: 0.810 A

Compressor current, specified value: 0.820 A

Rear temperature flap, actual value: 20, 0.0%

Rear temperature flap, specified value: 20

Compressor shut-off requirement, penultimate event: Low pressure event (gotta love the word choice!)

Compressor shut-off requirement, antepenultimate: Shut-off from Engine Control Module via CAN

Outside air temperature: 38.5°C

Outside air temperature, calculated internally: 31.0°C

Left front vent temperature: 10.0°C

Right front vent temperature: 9.0°C

Footwell vent temperature: 16.3°C

Temperature after evaporator: 4.3°C

Interior Temperature: 30.9°C

Sun intensity left: 750 W/m2

Sun intensity right: 690 W/m2

Blower status: active

Actual value for fresh air/ recirculation air flow flap: 60, 12.5%

Specified value for fresh air/ recirc air flow flap: 58

(Something obscured by a pop-up at that moment on my phone screen) "...stop for fresh air/ ...tion air flow flap": 210

Recirculated air stop for fresh air/ recirc air flow flap: 38

Left temperature flap, actual value: 28, 0.0%

Left temperature flap, specified value: 27

Left temperature flap, cold stop: 32

Left temperature flap, warm stop: 233

Right temperature flap, actual value: 25, 0.0%

Right temperature flap, specified value: 24

Right temperature flap, cold stop: 29

Right temperature flap, warm stop: 228

Front air distribution flap, actual value: 23, 0.0%

Front air distribution flap, specified value: 20

Front air distribution flap, air outlet stop: 234

Front air distribution flap, footwell air outlet stop: 25

Defroster valve, actual value: 243, 100.0%

Defroster flap, specified value: 244

Defroster flap, stop open: 239

Defroster flap, stop closed: 19

So. Yeah. There's that. Um. What does any of it mean?

(And, I didn't seem to have successfully captured anything about pressure :-/ )

thanks!

You will not find any data for 'AC clutch' as the Mk3 A/C system doesn't have one - the compressor is permanently driven via a sacrificial shear plate.

The reported shutoff due to low pressure event would be a clue pointing you toward lack of refrigerant, I expect.

31 minutes ago, Breezy_Pete said:

The reported shutoff due to low pressure event would be a clue pointing you toward lack of refrigerant, I expect.

Thanks @Breezy_Pete , yeah, guessed that; now, is there any way to get out of the system when that happened? We know that the system had been low (I had it recharged, and the amount of gas extracted was almost 50% low; I took these recordings after the recharge); my OBD11 never reported any faults in this system 🙄