Just brought a new Fabia Monte Carlo and discovered the Air Conditioning does not work. Checked with VCDS and the G65 sensor was showing 0.0 bar. Brought a new sensor still the same.   Even in open air I would expect a 1 bar reading.  So my next  educated guess was to try a new HVAC controller. So I pulled the old one out and noted its part number 5J0820045D. BUT Now I have a big head ache !!!   The two control cables for both the Hot/Cold Knob and the Air Outlet direction have become disconnected within the dashboard. I can see where the left hot/cold goes, not that I can plug it on. I tried and tried.

So I have 2 questions, where does the right Air Direction Control cable plug on ? How do I get access and also any tricks for plugging the left on. I must of tried for about half an hour and I was getting nowhere.

I'm almost at the point of giving up and admitting my mistake to the garage but I thought I would ask here first in case anybody has some advice.

You've assumed that G65 measures absolute pressure rather than gauge pressure, which I would suggest may have misled you.

Have you attempted to have it re-gassed? For it to read 0.0 bar you probably have a significant leak, but I think that should be your next course of action after reconnecting the cables. Not sure I can help with the latter, but maybe just keep removing trim panels until you have better access/visibility.

 

If you hover over the third image in this listing you can get a close-up view of the two cable sockets, which look to be keyed to ensure correct cable orientation , and latched on one side for retention. https://www.ebay.co.uk/itm/SKODA-FABIA-MK2-5J-2007-2013-A-C-HEATER-CLIMATE-CONTROL-PANEL-SWITCH-5J0820045C/263793354672?epid=1530077392&hash=item3d6b4f27b0:g:TLAAAOSwYRRbO1az

I read the bit at the bottom here with 

interest.

 

https://forums.ross-tech.com/showthread.php?633-Tis%92-the-HVAC-Season

 

The bit that says :

 

 

Added Information (12 July 2016):

G65 Pressure vs. Temperature chart
(When key is on, engine is off, static system pressure)

15C - 59F - 4.0 bar
20C - 68F - 5.0 bar
25C - 77F - 6.0 bar
30C - 86F - 7.0 bar
35C - 95F - 8.0 bar
40C - 104F - 9.0 bar 

Important to note about the G65 sensor: 
- A reading of 0.0 bar would indicate an absolute vacuum
- At Sea Level (atmospheric pressure) the typical reading is 1.0 bar

 

 

On my fully working Roomster I get a reading of 7.0 bar which seems to agree with the current temperature, but the Fabia shows 0.0 bar. That text says 0.0 bar is a full vacuum and I didn't see how that could happen. It was the fact it was telling me absolute vacuum that I thought it was not a regas issue.

 

Also those drive cables, they are attached to the knob control module. They have come off the real heater ventilation box buried round the back of the radio housing. I'm wondering if it's a dashboard out job. If so I'm giving it to a garage with my tail between my legs explaining what's occurred.

It's very annoying as I did not pull the module forward with any force, so they must pop off really easily. I've actually changed the same module on my Roomster due it saying memory fault and just blowing hot, I never had this problem on that.

Interesting, but I'm not convinced that is correct. 

 

Try connecting the loom plug to the sensor you took off and see whether it reads 0 or 1?

Edited 11 July, 20187 yr by Wino

It reads 0.0 in the open air, I tried that before I actually swapped it. I think I'm going to try it on my Roomster plug. See what that reads with the sensor in the open air.

Researching this gently, I came up with a completely forgotten experiment I did which was to unplug the connector off a working G65, yielding a 0 bar reading in VCDS measuring blocks:

So it does indeed look like a wiring/fuse/controller problem.  Sorry for irrelevance earlier.

Have you checked fuses, and wiring near connector for damage, and connector pins for corrosion?

Thanks, very interesting. I've measured 12v at the plug. I'm getting 12v from 2 pins referenced against a 3rd. I know one pin is a 50hz pwm output so I assumed one of my 12v readings was a high impedance input on the control module. But again I took the fact that I was reading a potential difference using all 3 pins then they must all be connected somewhere and the loom is not open circuit.

I'm going to get a 2nd hand control module off eBay and see if there's any change. After that it's going to a garage anyway to reconnect those dial knob cables but just in case a £30 pulled part fixes the AC bit then that's better than a garage charging me for a brand new one. Worst case it's £30 wasted.

I'll let you know the final conclusion.

The PWM output is probably pulled up to 12V at the control module end, pulled low by the sensor to send data, so that may be normal.  Can chuck a voltmeter at mine at half time to compare?

Not quite as I expected. With red meter probe on the pin at rounded end of connector, I read +12V with the black probe on either of the other pins.

Different from what you saw?

That's with ignition on but engine not running, with A/C button either on/lit or off. what conditions was your testing done with?

 

Though I can't see pin numbers or wire  colours at the connector, I believe the rounded-end pin is pin 3, 12V ignition live; pin at other/flat end is pin 1 earth, and middle one is signal/data.

Edited 11 July, 20187 yr by Wino

A friend has a 9N3 Polo with non-functioning A/C. G65 error for low pressure, and 0.0 bar showing in measuring blocks. I had a quick visual check of connector and wiring at G65, but nothing noteworthy.

Going for a re-gas attempt today, so it'll be interesting and possibly relevant to see how things stand after today.

Apparently cooling OK now. It's a 2005 car and the guy refilling it thought it may have never been touched since new. Not sure how he could tell though.

Gonna plug into it sometime tomorrow and look at the G65 pressures and compare with mine. If I get brave, I might extract my G65 and see what it says in air.

Just found this page : http://www.vwgolf.org/checking_pressures-1515.html which gives the impression of maybe being the source material for that bit you quoted from the 'HVAC season' thread; but I think what's said there - and the table titles - could be interpreted as meaning G65 reads in gauge/positive pressure, not absolute. What do you think?

 

(Struggling to make that link work here, copy/paste into address bar of browser and it seems to be ok)

Edited 13 July, 20187 yr by Wino

Oh !!!  Does that mean I've been wasting my time and it is a system pressure problem. I could kick myself now as I still have those cables needing reattaching. Hmmmm, not good but we live and learn.

I'll be interested if you now read about 7.0 bar in group 11 got G65 pressure.

That would kind of confirm I was wasting my time. Next weekend I try reattaching them cables but I think it's going to end up in a garage. My next hope is there's not a leak.

Thank you and I'll be awaiting your reading.

I'll see if I can find any info to help you with the cables, have you looked on workshop-manuals.com? Often has the info if you can put up with the pop-ups asking for donations, and have lots of patience trying to navigate through it.

Yes I've read them, they say dash out. I chatted to a Skoda man on Facebook (Skoda owners club GB) and he reckons it can be done with the dash in but it's very fiddly. I will be trying my best next weekend.

Also is regassing a normal AC requirement or does it mean there's a leak, even a slow one ? I ask as my 57 plate Roomster has never had a regas, I've owned it from new, so have I just been very lucky ?

Yes, people in the business say that it's normal to lose about 10% of your refrigerant per year. Probably a pessimistic estimate, and there's probably quite a lot of variability, dependent on usage levels, rad fan failures (leading to higher operating pressures) etc. 

Right then, step 1 is get those flex shafts reconnected and then step 2 I'm going to put both the Fabia and my Roomster in for a regas.

Fabia works again. I managed to reattach the left cable (hot/cold). But I had to get a garage to attach the right hand one (air outlet choice). They did that and re-gassed it. Now all blowing cold again.

So I will never make that mistake again, G65 at 0.0 bar means No Gas.

£182.99 in total garage charge.