Another one (n280) bites the dust
Hello everyone and thank you for the huge pile of information present on this website!
I own a 2007 Skoda Octavia MK2 (pre-FaceLift), 2.0 TDI, 104KW/16V, BKD engine, 2-zone climatronic
I can state the following (cronologically):
1. Car purchased 2010, 140km (87k miles), now it has 260km (162k miles)
2. AC had no issues what-so-ever until last year.
3. About two years ago I had a problem with the engine shutoff valve (that thing that cuts air to the diesel engines so that the engine stops nice and smooth); my car would literally rock when I would stop the engine... That shutoff valve would blow some green fuse in the engine compartment every other engine stop... Guess what: I have been told that the same fuse also feeds the fans (or the small fan.. don`t remember)... So my compressor/valve might be cooked. Will check for black deposits when changing the RCV (wish me lucj, I hope there`s no black death).
4. However, diagnosing and fixing that issue took more than 3 months since my (former) mechanic did not had time for me and later he kept on postponing me, telling me that I have some tired engine buffers (supports)... Guess what: three months later I changed the mechanic and the new mechanic fixed the issue very fast. He also replaced one engine buffer as the engine rocking literally tore it off.
5. The new mechanic also asked me when was the last time I have refilled my AC... I had no idea (not in the past 4~5 years, though)... Yet, it was blowing ICE COLD air.
6. Same year, later on (in the autumn), I detected some delay in cooling (about 30 seconds or ~half a km/mile).. I discussed this with my new mechanic and he showed me the AC machine summary (+60grams refrigerant / +5g oil).. No other problem. darn...... (my question now: might he had used some low quality compressor oil?)
7. Next year the delay problem seemed gone until in the middle of the summer.. small delay, yet after that the AC was blowing near 0 Kelvin (-459F lol ) once it started to blow cold (that is very very cold, I did not considered the delay to be a problem, I was not aware of any delayed cooling issues).
8. This year however... I noticed the delay problem was worsening... I took my VCDS and noticed 5bar (~72.5psi) when compressor was fully on, yet blowing slightly cooler air. That is - it was low refrigerant (~23*C / 73.4F ambient temperature). I went to an AC shop and had them refill my system. Very helpful and kind AC shop mechanic told me that I might have a considerable leak (AC machine recovered only 45g/1.56oz- yes, that is forty-five grams or one point fifty-six ounces - of refrigerant)... After recharging he checked for leaks with some gas detection probe and told me that my condenser is pierced like a swiss cheese.. too many rocks hitting it (not the bugs, don`t blame the bugs). 3 days later I had him change the condenser and I had already lost 160g (5.65oz) out of the 525g (18.5oz) inside.
9. The test after showd no improve... The AC sop mechanic told me that it might the AC controller unit that needs to be changed.. Well well, I remembered tampering with the entire car dashboard (radio-mp3 player / climatronic / etc) until I found out how to install the 7D aux heater module.. However, it`s not here, as I did not break any connector and I correctly seated every single one of them. All temperatures are reported correctly, all flap positions are ok... not from there.. I also readapted the climatronic several times, no improvements.. I intiially thought that the aux heater module would turn on (I suspected a malfunction) and heat the air while ECON was off... VCDS proved me wrong (same happens when the Aux Heater is uninstaleld in the gateway installation list or with its CAN plug unplugged).
10. Now the AC has either small or long periods when it won`t work (that is - blowing slight cooler air, maybe 5~10*C/9~19*F cooler than outside temp), blowing (very) hot air when idling (e.g. at traffic lights), refusing to start.. However, sometimes it blows very cool (although not polar cool) air, even with 37*C (99*F) outside temp and after some minutes I have to move the air vent away from me. When it simply doesn`t want to work, I turn the econ mode on and off several times, quick enough (0.5~1 second between pressing the button; I have followed the current intensity value with VCDS, it no longer drops to 625mA as it did a couple of months ago, but it stays at 825mA; however, as I am an embedded hobbyist, and with physics background, I suspected that repeatedly engaging the system would eventually unblock its valve for some time... true, it saves my ass for the moment, but next time it`s the same. Yet, it only works if the engine is hot, that is if both fans are spinning)
11. The small fan never starts spinning when the AC is turned on and the engine is cold. The delay is caused (I suspect) mainly by the non-spinning of the small fan (which sometimes doesn`t spin for 8 minutes while the car idles)... Once the engine temperature raises over about 50*C (122*F; oil must be much higher, ECU knows best why it requests both fans to start), the compressor engages and I can feel the AC condenser warming up from the passenger side top corner and the car blows slight cool air (usually in the mornings, outside temp is below 30*C/86*F).
12. Measurements while the AC is blowing hot air: N280 current is 825mA (specified at 820mA), compressor load is ~3.5Nm (2.6lbsf.ft), high-side pressure ~8bar (116psi), evaporator temp ~26*C (79*F), ambient temperature 24*C (75*F); interesting fact: small fan is spinning at 25.6% when specified value is 30.4% and 24.8% when specified value is 30%. I`ll have to check this fan (its brushes) as well when I switch the RCV.
13. Measurements while the AC is blowing slightly colder (or maybe even cool) air: N280 current is still 825mA... compressor load 6+Nm (4.43+lbsf.ft), high-side pressure ~12bar (174psi), evaporator temp ~10*C (50*F), small fan 53.6% (not sure about spec`d value), ambient temperature 28*C (82*F).
14. I went to a compressor diagnose with gauges (costs about 13USD) and low-side pressure is about 4bar (60psi)... dead valve for sure... I was told I should rather replace the entire compressor and drier plus wash the system, but that is pretty expensive (850+ USD for all the fun). I have rather ordered the n280 valve from some online auto parts store at 55.6USD including shipping. Evacuating the installation, vacuuming it and refilling would cost 13USD plus the additionally required refrigerant. That`s a bargain compared to the whole compressor... Yet, I`ll have to check what color is inside my compressor...
Fun fact: Before ordering the new valve I wanted to be 100% sure that I order what I need, therefore I went to a mechanic to undo my car`s belly for me to take a photo of the compressor label... Done quickly, in under 2 minutes the car was elevated and its belly taken off. Sure thing, the compressor was all dirty (I had some diesel leak from the tandem pump metal seal, which seal I have changed a couple of years ago) with diesel and dust... The "smart" mechanic took a brake spray (containing solvents) and cleaned the label... He cleaned it for sure, it was all white afterwards
)))) not even a letter remained! However, based on some photos and car`s VIN number, the online shop helped me pick the right part (snap ring type one, round bump, yet a different type than what I have ordered) -
https://drive.google.com/file/d/0B8BqzWJzQpE1T3IxNHdxanVWZUU/view
ordered
https://www.epiesa.ro/supapa-regula...mo-v15-77-1014/17971/100354/idprod-288640591/
was adviced to order
https://www.epiesa.ro/supapa-regula...otec-ktt060034/17971/100354/idprod-509611987/
anyway, now I suppose I have this part installed:
https://www.epiesa.ro/supapa-regula...otec-ktt060004/17971/100354/idprod-509611683/
I hope there`s no problem with posting the links.. If it is, the admin can remove them as he wishes
I hereby thank you all for all your contributions!
Wish me luck with the compressor!
