Hi folks. I have a problem with the airconditioning in my 2007 Octy Scout.

 

I'm hoping that knowledgeable peeps on here will be able to offer explanations as to why particular components/faults should be considered/excluded as the cause of the problem, and how I can check. Other than a refill, I haven't replaced anything yet, as I'm hoping the collective Brisky wisdom might point me in the right direction before I spend what little spare cash I have on the wrong thing.

 

I've surfed this site a great deal in search of answers, but my specific set of symptoms has eluded me and I don't have a clear idea about how to proceed.

 

Before I continue  , this has all been checked out using VCDS (thank you nopowerman!) before, during and after exhibiting these symptoms, and no fault codes were present. I have also used the Climatronic hidden information menu to check values.

 

Symptoms:

So, despite the requested temperature being set to LO, ECON definitely OFF, and the ventilation fan set at maximum (engine running), the output temperature of the Climatronic on my Scout oscillates between cold (can be as low as 10-12degC, what I'd expect it to be, but often only dips to late-teens before warming up again) and not cold (a value that can be dependent on the outside temperature) according to what can be felt at the vents, and confirmed by menu items 6-2 or 8-2 (LHS and RHS vents), . The rate and duration of temp change varies, as does the time spent at the extremes.

 

Deduction:

Whilst the temperature is cold, I have noticed that system pressure value (menu item 10-1) has increased to between 9 and 11bar. When the temperature increases, the pressure has dropped to 6-7 bar. It seems that this is the core issue, but I don't know what prompts the pressure change, whether it's a duff sensor or control module

 

History:

About 3 weeks ago the car had a re-gas which was prompted by lack of low vent temperatures and some oddly abrasive noises when the aircon was previously operating. After checking searching this forum, I went for a refill. No leaks were found but I wasn't charged because there was insufficient improvement in cooling performance according to the company policy (ATS). I was told that although it was leak-free and had filled correctly, there was a fault somewhere in the system that prevented it from operating correctly, suggesting a fault with a sensor, valve or the compressor. They didn't say how much residual coolant they had pulled out. The grinding noises appear to have gone.

 

 

Supporting information:

Compressor speed (19-4) seems consistent at engine speed + a bit (value 10 at 800rpm tickover, increases according to rpm). The compressor code (11-6) always shows 00.

 

Some odd values I noticed earlier from the hidden menu:

4-2 (External Temperature, Temperature Intake degC)) 63.5  - this when MFD showed 22.5, as did 4-0 (Ext. Temp, Temperature External degC) and 4-1 (Ext. Temp, Temp Ext CANBUS). It was hot in the car at that time, but not 63degC hot!

17-0 (Temperature Internal Recirculation, Setpoint Value %) flashed alternately between 00 and 001 (small 'one'), as did 21-1 (Air Distribution, Face %), 21-4 (Re-circulated %), and 21-5 (Air Sensor %).

 

I've also noticed when checking this out with the bonnet up that the condensor fan doesn't seem to run very often, but when it does, it only seems to run at full speed. The temperature vent output temp drops accordingly when the fan is running.

Potential culprits seem to include (but are not limited to): Pressure sensor; pressure regulating valve; fan controller; various temperature sensors; low coolant level/pressure; compressor central shaft loosening/failure; compressor seal wear; ...... BTW, which is the compressor manufacturer to avoid?

 

I have full data from the hidden menu (taken yesterday), and the log summary from the VCDS scans if it would help to post those.

 

I look forward to your suggestions and being pointed in the right direction.

 

Many thanks in advance.

 

Adam.

1 hour ago, tintinandcharlie said:

Whilst the temperature is cold, I have noticed that system pressure value (menu item 10-1) has increased to between 9 and 11bar. When the temperature increases, the pressure has dropped to 6-7 bar. It seems that this is the core issue, but I don't know what prompts the pressure change, whether it's a duff sensor or control module

 

 

That is normal, its the pressure measurement on the high side circuit, when cooling is commanded the electronic operating valve will make the compressor pump, the high side will rise and the low side will fall.

 

If you look at the measuring block for cant recall the name, might be turbine voltage, its the modulated voltage applied to said valve, it will be increased when you see the increase in pressure.

 

Leave that measuring block open and look at the other sensor values and you will see which one is causing the cooling to stop and start again, its output should lead the turbine voltage and system pressure.

 

Bad explanation, hope you can make some sense of it.

@tintinandcharlie - Has the cabin pollen filter been replaced recently?

I got the car in December, but I can't see it in the receipts that I have. How would that affect things?

I too have the same/similar issue.

 

I had the condenser replaced after an age/corrosion leak and the system was flushed.

 

It now takes 5-10 miles running before it starts to cool and even then it's not icy cold and comes and goes.

 

I suspect the solenoid valve on the compressor is the issue, probably from debris in the system.  I have noticed that the commanded voltage sent to it ramps up slowly which doesn't help a sticky issue. With the engine running, when the plug to the solenoid is pulled and reconnected it gets an instant ~14v and usually the compressor will then work.

 

The part is cheap enough ~£20 and a DIY job however handling the gas side of things is the snag so eventually a trip to a shop is inevitable if I want things working properly again.

 

It should be mentioned that I ran with the Aircon INOP for a few months which is why I suspect the system got contaminants and the shop flush wasn't thorough enough.

 

The solenoid itself seems easy enough to strip and clean if you were that way inclined, again it's the gas that's the snag.

I replaced my 280 valve after rebuilding the first one, both appeared to be working on test but would not ramp up the high side pressure, eventually replaced the compressor and all was well till the pulley splines went on the new one, did not know till it was removed so cost me another pump and yet another recharge.

 

When I stripped the first pump it was in spotless surgical condition, completely unworn so I still think the problem was the 280 valve and probably a half functioning  cheap replacement, I had already gone through 2 high pressure sensors before getting a good one, the price to pay for all these cheap risky components is the regas charge every time, I have now bought my own guage set, vacuum pump and do my own recharges using gas in small canisters from China

Hot weather update:

14 bar seen on the hidden menu 10-1, but also mid-7s within a few minutes. I'm hoping that this implies that the compressor might be ok, and the fault is with either a sensor sending the wrong info about temp or pressure to the controller, or a sticking/faulty pressure regulating valve. If the main shaft is loose, would that cause this irregularity?

I've seen a suggestion to clear debris from the front of the condenser, so as that's a free fix I'm going to check for this evening.

As it's cheap, I'll also change the pollen filter this week to make sure that's not a contributing factor, but I really don't want to get into a game of component bingo so I'll try and get on a vcds system. Can a clever person please tell me what I should be looking for within the HVAC block in terms of correct readings and what would signify a fault? I'm assuming that I'd be looking at input and output temps, pressures, electrical requirements, and command signals

 

Thanks.

 

 

I used the measuring block function to watch how my system performed at tickover during the hot weather today.

 

You can watch 3 groups of 3 measuring blocks at a time.

 

I have no short term memory so I apologise because I cant recall the terms used which are not particular descriptive.

 

I would initially watch the voltage to the N280 valve and the pressure sensor values whilst switching from aircon LO setting to ECON, on low you should see the voltage rise to some odd figure like 8.65 or 10.5 volts (sorry, my memory again) and the high side pressure rise, the low side will fall but it isnt measured, mine went up to 20 bar today which is actually 19 bar guage pressure.

 

The 3rd measuring block group should be the evaporator temperature, mine went down to 12°c today when ambient temp was in the 30's.

 

Dependant on what the above gives you then you can look at fan speeds, outlet vent temperatures, temperature sensors, flap positions basically all the inputs and outputs.

 

Hope that helps.

Will have a better look at this tomorrow if I get a chance, but is there just one radiator fan or two?  The comment below makes it sound like just one? Or are there two and this is referring to the smaller one?

 

On ‎20‎/‎08‎/‎2019 at 12:58, tintinandcharlie said:

the condensor fan doesn't seem to run very often, but..

 

I didnt think my fans were turning very quickly, perhaps the controller ramped them up further once the refrigerant was recirculating, certainly when I shut the engine down the over-run noise and wind rush from the fans told me they had been working very hard.

 

On VCDS though it showed the (forgive my memory again I cant recall the terms) fan percentage actuation rising to 100% but the actual actualtion or whatever the term was only went up to 82%, like many of the parameters I dont  think that it can measure it and is using a calculated value, if not what does the imbalance between the figures suggest?

On 20/08/2019 at 16:03, tintinandcharlie said:

I got the car in December, but I can't see it in the receipts that I have. How would that affect things?

I didn't see this until now. A blocked pollen filter will reduce all airflow through the ventilation system.

8 hours ago, KenONeill said:

I didn't see this until now. A blocked pollen filter will reduce all airflow through the ventilation system.

The airflow from the vents seems adequate. Not a hurricane, but by no means a butterlfy wafting through a straw...

 

18 hours ago, J.R. said:

 (forgive my memory again I cant recall the terms)

 

Without being funny in any way, would a video clip help (if you are so inclined) as a note-taking medium...?

 

Thanks for your input, BTW.

 

T

Beyond my skillset and when I was doing it I did not know that I would be recounting the experience.

 

In any case I would have to have a video running 24/7 and as when someone once suggested that I put up a webcam or time laps camera to record my renovation of my building I said all you would see is a bloke walking aimlessly around scratching hs head wondering where he put down the pencil/tapemeasure/hammer/screwdriver etc 3 minutes before.

 

There are worse things in the world than not being able to recall a term that is usually meaningless anyway.

On 27/08/2019 at 21:15, Wino said:

Will have a better look at this tomorrow if I get a chance, but is there just one radiator fan or two?  The comment below makes it sound like just one? Or are there two and this is referring to the smaller one?

 

 

There's two, one large for the main cooling system (RHS as you stand at the front bumper looking at the engine bay), and a smaller one low down on the left for the aircon condenser.

 

14 hours ago, J.R. said:

Beyond my skillset and when I was doing it I did not know that I would be recounting the experience.

 

In any case I would have to have a video running 24/7 and as when someone once suggested that I put up a webcam or time laps camera to record my renovation of my building I said all you would see is a bloke walking aimlessly around scratching hs head wondering where he put down the pencil/tapemeasure/hammer/screwdriver etc 3 minutes before.

 

There are worse things in the world than not being able to recall a term that is usually meaningless anyway.

Fairy nuff. I'm the same with my DIY so you have my sympathy. Spend most of my time going back to get things I put down in the wrong place and the rest calling myself all kinds of idiot...

Unfortunately, I don't know much about the 'fan control module within main fan' set-up that I think is what you have, but I'd be surprised if the smaller fan isn't supposed to be speed controlled, which I believe the main fan is, both by this module.  I'm not sure how the fan control module gives feedback to the rest of the systems about what it is actually doing versus what is commanded, but I guess it must be via the green wire to the engine ECU, some sort of 1-wire two-way comms.

Other Mk2 owners will hopefully be able to comment on the variability of speed of the fans?

 

Something is causing the compressor to back off completely (when the pressures drop back to 6-7 bar) and that something isn't being detected as a fault situation by the various monitoring systems, which is a shame.  I guess I'm not exactly giving you news here, sorry.

 

Just scanning your opening post again I don't see reference to figures for demanded and actual (radiator) fan speeds, do you have that data?

 

 

 

 

 

 

Edited 29 August, 20196 yr by Wino

Researching this a little, it seems like maybe there isn't any real feedback from the fan control module. This article about someone fitting mk5 Golf fans into a mk2 Golf and using a DIY control system seems to suggest the green wire is just a PWM control signal. Also seems to confirm my suspicion that the fans should work in tandem, speedwise?

 

Here's an interesting quote from that article: 

"The J293 controller incorporates a failsafe mode where, should there not be a recognized PWM signal of between 5% and about 95% within 10 seconds after 12V is present on its engine alive KL_15 terminal, it runs the pair of fans at full speed. "

 

Edited 29 August, 20196 yr by Wino

Here's a translation of some more info from motortalk.de

"Function of the two electric fans (motor fan) A few general information ...There are two versions of the dual-fan system on the PQ35 platform - depending on the engine and features installed:- 500 W system- 350 W systemThe 350 W system is powered by Siemens VDO and Conti-TEMIC. The 500 W system from Siemens VDO, Conti-TEMIC and GATE (Italian company).How the dual-fan system works ...The master fan (large fan) contains a control unit that allows stepless speed control of the two fans. The slave fan (small fan) is co-supplied and controlled by the electronics of the master! The slave is a "stupid" DC motor without its own "intelligent" electronics.As a first important note should therefore already mentioned here: The only way to reliably determine whether the slave is actually broken or not, is to remove the slave and a DC voltage of max. 1 volt to the two pins to lay (Attention !!! It is a pure DC motor! That is, more tension -> more speed -> finger off !!!). At about 0.6 ... 0.7 volts, the fan should turn slowly. Ergo: he can not be faulty, because he does not contain "intelligent" electronics and is only controlled by the master. Often the output stage for the slave in the master is defective, whereby the slave does not turn anymore, but of course is not defective! Therefore, you can not detect this error with an actuator test via the guided fault finding, because the control is done by the master. Everything is fine so far?Further note: One should not mix the fans of the manufacturers with each other. So no Siemens master with a Conti-TEMIC slave etc.GATE fans also have a different mech. Plug coding. You can not mix with Siemens or Conti-TEMIC anyway, because the plugs are not compatible (unless you damage the plugs, which is not recommended in terms of possible moisture problems).Another reason against mixing construction: The fans of the various manufacturers turn partly in different directions, which can significantly affect the air performance (ie the cooling capacity) when mixing the fan. This risks overheating of the engine.But continue to function ...The control electronics in the master has its own power amplifier for each fan. The control is independent, but in normal operation with the same duty cycle (TVH). The speed is controlled by a pulse width modulated signal (PWM signal) at a frequency of 25 Hz provided by the engine control unit (MSG).In the absence of a PWM signal (constant high or low) and existing voltage at terminal 15/87, both (!) Fans are operated in emergency mode (maximum speed)! With a TVH <5%, the fans also go into emergency mode. The emergency starts at the earliest after 10 s!Now, an interesting question arises ...Can it be that in certain situations only one fan is running?No! The engine control unit sends only one (!) PWM signal via pin 3 of the plug to the master. As soon as one of the sensors in the engine compartment transmits a value to the MSG, the MSG causes a PWM signal of e.g. To send 15% (smallest TVH from which the fans rotate) to the master, both (!) Fans must slowly start to turn. The statement that the slave is only responsible for the air conditioning is simply wrong.If you have the friendly perform a so-called "actuator test" and both fans start, it is safe to assume that the fans i.O. are. Unfortunately, the workshops carry out the actuator test only very rarely, as this is not automatically retrieved in the guided troubleshooting - a "historical" malfunction.I hope to shed some light on the dark secret of the dual electric fan (or casual engine fan) of the PQ35 platform …"

 

Apologies for the loss of formatting.

TT&C.

 

Its comforting to know that i am not the only one and it would have happened anyway with age, I still hear my fathers words "dont ever grow old son!"

 

Wino.

 

I am going to hook up VCDS and force my fans to operate on low and high speed, its very hot at present & I get the feeling that the fans aren't doing all that they could when the car is not at high speed, be good to know they are OK.

After Aston Bodger very kindly gave up some time on Sunday morning, the N280 valve is the prime suspect. It definitely has one (we unplugged it during the investigation) but can anyone recommend a source for a replacement and how I ID the correct part required? Will I be able to get a compressor part code from the VIN via the stealer?

 

Cheers.

 

T

Edited 10 September, 20196 yr by tintinandcharlie

I think your compressor will be the Sanden one listed here, 1K0820859QX https://skoda.7zap.com/en/cz/octavia/oct/2007-419/2/260-260020/#1

The N280 doesn't jump out at me as a separate part within ETKA, but this one lists the 1K0820859Q amongst its applications, I think: https://www.onlinecarparts.co.uk/aks-dasis-7522546.html

Not cheap though! Maybe cross reference against the compressor ID numbers shown, which ought to be on your compressor somewhere.

Cheers Wino.

 

I have previously checked here:

https://skoda.catalogs-parts.com/#{client:1;page:part;lang:en;region:cz;model:octavia;modification:oct;year:2007;modetype:419;group:2;subgroup:260;pnc:260020}

and your suggestion is the same number but I've read some conflicting reports about different manufacturers for compressors and wanted to be sure before ordering a valve. I'll have a grovel underneath at some point to check.

 

On Fleabay:

https://www.ebay.co.uk/itm/A-C-Air-Compressor-Control-Solenoid-Valve-For-VW-Golf-Jetta-AUDI-A3-1K0820859S/142115109955?hash=item2116b87c43:g:em4AAOSwa2pbMgqF

 

Or some more confidence here:

https://www.buycarparts.co.uk/nrf/9666076

 

 

 

T

 

There is a sticker on the compressor with the manufacturers name and the VAG part number, cant be read directly but with a mirror or camera phone you will have what you want.

 

I had at least one faulty non working cheap replacement valve and even with the one that bench tested OK my compressor refused to pump, stripping it down revealed nothing but it all fell to bits in my hands and I bought a new compressor which worked fine till the pulley stripped its splines because the nut had not been tightened.

 

Trouble is each time you change it you swallow the cost of a regas so you want to be sure it works, I would leave the old compressor in place, remove the plug and connect the new valve, run the engine, switch on the aircon and see if the valve operates, its only a tiny movement, there is every chance that your old one can be revived or that there is a foreign object obstructing it but the cost of the recharge means its better to have a new one but one that you know works, dont buy the cheapest like I did as usual.