J.R.

Yes I had thought of that and also the problem with modern LED lamps, the El Cheapo trailer lights that i use (€1.45 each) still use bulbs and will probably always remain that way, they no longer come with bulbs which would equal the cost of the lamp unless you buy them by the box as I do. Thay are crap and the slightest vibration or damp has them playing up, the trailer & caravan manufacturers have all moved to LED light units for reliability. Every VAG & Westfalia dedicated wiring kit with a Trailer Module canbus node and coding instructions have a 13 min socket and not a 7 pin one hence my scepticism that those who have been relieved of lots of money are actually getting the supposed safety from the vehicle stability systems that they believe they are. Your Polo with the additional coding would no longer be able to give a bulb warning if a brake light bulb was used instead of a rear light bul but it was a smart attempt at trailer detection. The new high impedance bypass relays do a much better job of detecting when there is an indicator bulb connected and sounding the audible alarm than the older thermal type, one of those could be made with a "trailer connected" output when it detects a bulb or maybe even LED load on more than one or two of the lighting circuits, that could then be used as the input to a canbus trailer module. I reckon within a couple of years there will be a cheap way for me to upgrade with a generic trailer module and bypass relay, perhaps both built into the same unit, all the vehicle systems need are to be coded to communicate with a trailer module and for that to tell them that a trailers electrics are connected.

In the self study guide there is a plethora of 3 letter acronyms, there is an amazing range of electronic aids that can be integrated using only the yaw sensors, wheel speed sensors and the ABS controller, a fascinating read if that your bag!

Pressure will be the same on bolth low and high side, the high side only increases when its pumping with sufficient refrigerant. Do it with the engine running and keep an eye on the guages, the high side pressure (relative to ambient temperature) will tell you when you have filled it sufficiently, without vacuuming down and special weighing equipment its the only way you have to know whether the charge is sufficient. Youtube is your friend.

Warm the canister in a bowl of hot water to get more out of it if you are feeling lucky, your eyebrows will grow back eventually!!!

I would like to know what this non R134a non ozone depleting snake oil gas is especially as they claim a full charge can be done with one 168 gramme canister. I do hope its not Butane gas R600. Please let us know how you get on

You could well be surprised, I repaired a written off Sierra (several actually) on one the aircon condensor was bent like a banana I was at the point of removing it when I had the instinct to press the valve first, it had pressure!!! I had to do the repairs leaving it in situ, the aircon barely worked as the charge was insufficient but was fine when I had it recharged, the Fred in a shed back then had no more equipment than I did and did not vacuum it down. The system will stop when the pressure drops beneath IIRC 2.7 bar absolute pressure, you could drive round for years like that before the natural losses leaked out everything. OTOH if there is a leak you will be tearing it down anyway, its a £60 saving if you can delay buying the vacuum pump.

ASC does not activate the rear brakes per sé, it will pulse the brakes on the inner side of the curve to counteract understeer and priveledge the front brake to effectively create a turning moment about the inner front wheel, having inwardly digested the VAG self study guide on ABS and electronic stability systems I dont think there are any that solicit the rear brakes. If you use these vehicles in anger its the rear brakes that take the greater hammering.

Did you get any visual confirmation on the second car that the vehicle had recognised a trailer was connected? The only way that it could be achieved is to do without the foglamp connection (I never use foglamps on a trailer anyway) and use the extra contact (used to cut out the rear foglamps when towing) to drive a relay reversing the N/O to N/C and use that output for the towbar controller input. I dont think any of the places that fit the proper kit would bodge around like me and remove the foglamp function from the towing electrics. My belief is that a vehicle with a 7 pin towing socket cannot have the "dedicated" towing electrics where the vehicle electronics know that a trailer is being towed and change the vehicle stability systems, - unless someone can prove me wrong and explain how the trailer connection is detected, I really would like to know because it will be an interesting project for me and I will be able to see whther there really is any noticable difference.

You could depress the Schrader valve with a pointed implement momentarily, if any gas comes out you have pressure in the system so no air contamination, you may have said you have VCDS, with that you can also check the high side pressure, be aware that it give absolute and not guage pressure. You wont damage the compressor by turning on the AC without regfrigerant, if the low side does not have the minimum pressure then the climatronic controller will not command the solenoid valve, the pump turns all the time anyway, it will just continue stirring nothing but PAG oil.

Never heard of that. Have you actually recieved your camping gas R134a? Are you planning on getting it from Ali-Express? My first order was OK but there is a lot of wastage once the system has some pressure in it you can get less and less of the can contents into the system. All my subsequent orders never arrived, a lot of the listings did not actually have the regfrigerant when you clicked on them, just options for dye, oil, test kits etc, any that did sell it had to call it something else, basically I think it got shut down hence my move to a garage type cylinder which was loadsamoney but at least it keeps me away from the incompetent idiot robbers in the fastfit places around here.

That looks the same as mine which works OK, you will need to buy the special expensive oil that it uses as they are shipped dry, dont forget or you will destroy it straight away.

It wont be fine without a sensor, as fine as a blind driver would be! You can bet your arm that the sensors will work on another car or they have found a way of making them work or they would not be getting pinched. Yet another reason for me to never buy a newer car than the one I have. Are you saying that they removed the cover but did not steal the sensor? The exposed wires make it sound like they did steal it, maybe they were disturbed.

Maxspeeding rods are a good company, I have bought a couple of aircon compressors and rear brake calipers from them.

You wont be able to add oil or dye unless they are in containers pressurised to 4 or 5 bar, with a vacuum pump and guage kit its very easy to draw in any fluids, maybe some of the Chinese refill cans contain dye?

If your system still has some charge then you will be able to top up with the cylinder, are you buying a proper 6kg one or the Chinese camping gaz type cans? I started with the former and then supply problems (the tin cans are illegal in europe) forced me to the proper cylinder which no compliant seller will sell to an individual without the required certification, some of the eastern european E-bay sellsrs will though. If you have a leak or replace any component like an O ring then if you try to refill from your cylinder without a vacuumpump you will only get a partial charge in there and it will have 20-25% of air floating about, dont even think about trying it, vacuum pumps are not too expensive in the scheme of things after spending £30 on guages, £200 + on an R134a cylinder etc. Where it gets really expensive is the equipment to recover & recycle the existing regrigerant gases without creating your own personal hole in the ozone layer.

On a 7 pin towing socket? I would love to know how that works as it is what is stopping me from fitting a proper towing module. My Yeti does not have reversing sensors and had a basic head unit with simply a radio tuning display. 7 or 13 pin electric socket? Do you believe that if you had a proper dedicated and coded towbar installation on the Tiguan that it would not have used the rear brakes when you were towing?

I believe that the "dedicated" electrics if they use a 7 pin socket are no more than a modern low sensing current bypass relay as I have fitted, perhaps someone will correct me but after resaerching all the wiring diagrams it is my understanding that two of the extra terminals in the 13 pin socket are used to sense when a trailer plug is fitted on the proper VAG or Westfalia dedicated electrical set up which communicates with the vehicle systems when coded in. A 7 pin socket cannot do this. My neighbour was certainly sold his installation as being "dedicated" and integrated but it was nothing of the sort, he paid a kings ransom for it and deserved better.

A good price you had back then! Towbars used to cost me £35 but once they had to have EU testing and certification the price went up considerably. My Yeti is no less safe than any of my previous cars that I have fitted towbars to, no less safe than your 2005 Superb was, in fact its considerably safer than any of my previous towing rigs, could it be safer? Probably under some theoretical conditions that as a responsable driver with 45 years towing experience I wont be experiencing through my own actions, am I bothered that the trailer dose not show up on the radio display? It never would have done with the radio that my vehicle came with. I completely respect your decision to say you choose not to fit a towbar any more, it will come to all of us one day but to say "no longer take the risk"? - Do you consider you were taking a risk when you fitted your previous towbars? My UK neighbour has been fitting towbars & towing for a decade longer than me took the same decision as you for his Octavia MK3, he was scared to death with the tales of Canbus which really meant he did not understand it, he paid for a profesional to fit his and i suffered problems which they were either incapable or unwilling to resolve, he would not let me near it for fear of the Canbus being disturbed, it was only after getting VCDS that I realised I had had canbus for 13 years on my MK1 Octavia and never even realised, when I had to sort out the mess of the professionally fitted towbar on my MK2 Octavia (previous owner had it done) I then knew enough to persuade him to let me sort out his professional scotchlok & twisted wire bodge up and to show him that he actually had a bypass relay no different to the ones that he had been fitting for decades except that it was far better constructed, only took milli-amps from the bulb circuits and had a far superior sensing mechanism for the audible warning that the trailer indicators were working.

You are correct Wino, however if you have vacuum tested it only to find that it has a leak then in doing so the system will have been purged with ambient air. Hence my comment starting with "if you have vacuum tested it....................." I have recharged several systems that have been open to the elements without changing the drier and there have been no ill effects, the procedure says to leave the vacuum pump on for 45 minutes/one hour etc yet it pulls the full vaccum within a couple of minutes, I wondered whether this would be to allow time for any moisture to vaporise and be evacuated?

My Yeti towbar was £105 and £20 something for the wiring kit, I presume at £150 you were DIY'ing, you can still do so if you are minded to.

Great news, if anyone does a scan with decent diagnostic equipment like VCDS it will bring up a couple of fault codes, if they have any nouse they will know immediately what it is, if not then you should tell them, dont allow a garage to rip you off investigating a fault thats not a real fault or a buyer to knock you down or a dealer if you trade the car in.

If you cannot pull a vacuum to test then it means that the leak has already allowed the system to be filled with damp ambient air, aside from whether you replace the drier cartridge when you do get it up and running it means you have nothing to lose by compressing the system with air to test for leaks with soapy water.

You never said that your system was empty, that was why I asked what the pressure was. Like you I invested in the test and filling equipment, you will need the vacuum pump for refilling from your cylinder. My leaks in the past have always been from where I have refitted a compressor and damaged the O ring on the large connector when refitting it, in hindsight each time it happened I felt some resistance. The VAG O ring sizes dont come in the boxes of assorted O rings, they are larger & a different cross section.

Aj77, do you know what your system pressure is? An Octavia 2 will have already needed a recharge by now through normal refrigerant losses through the flexible hoses, O rings etc without any of them needing replacements. The G65 refrigerant pressure sensor often fails through corrosion where water sits on the aluminium casing which will cause the system to lose its pressure.

My module was under the drivers seat, it will be under one or the other beneath a plastic protection cover. The fault codes only showed up during a VCDS scan, what I cant recall is whether there were warnings on the dashboard MFD, I dont use a phone in the car, mine does not have Bluetooth anyway, the car was forever looking for and trying to connect to the phones of previous owners.