Aircon issue - regas required or something else?

[Maggle]

My aircon is no longer supplying ice cold air, even on 'LO' setting, and is hissing quite loudly. Is it simple a re gas that's required or is something else wrong? Any help/advice greatly appreiated.

[petrolcan]

Most likely a regas will sort it. Any decent tech should test the system for leaks before refilling the system.

[jimbojames]

I've just had my 2014 Octavia regassed for the first time since I got it. The tech pulled a vacuum on it first and left it for about 10 mins while we were chatting to check for leaks. None found, so regassed it, back to ice cold. 

 

Don't take it to halfords are similar, they don't vacuum it first, they just use the little disposable bottles to jam as much in as they can. 

 

Find a back street garage somewhere that does regassing, they tend to have the portable machine on wheels to vacuum and regas.

[jimbojames]

Well, seems lack of gas wasn't the only issue, I'm back to no more cold air today. 

 

Checked with my obd11, and I still have 5 bar of refrigerant pressure, so that's fine. When I turn on the air con, the compressor current is reading 0.82 Amps. Anyone know if this is normal? 

[J.R.]

It is a meaningless figure all it is telling you is it thinks it is pumping because the modulating valve is being pulsed and that is what the calculated current would be, it's not even measured.

 

That you have no cold air tells a different but true story.

 

Why do you say that 5 bar refrigerant pressure is fine? That would correspond to the low side pressure at circa 23°c without the system running, the system measures the high side which will be in equilibrium with the low side when not commanded = not pumping or cooling.

 

The high side should rise to 10 bar at which point the fans will cut in, the flow is then regulated by the modulating valve till the high side pressure stabilises at around 6.5 bar, the low side pressure (which you cannot see) will drop proportionately.

 

It sounds like you have a near fully charged system, my guess is the modulating valve is sticking or the shear plate has gone on the pulley, the latter can be checked visually.

 

Most of the VCDS measurements are useless and simply calculated values, the compressor shut down codes are very usefull but I'm not sure if you have access to them, most of the time VCDS will say it is working, ie commanded and no fault codes yet the evaporator temperature tells a different story, at that stage you need someone who knows how to work with their hands and eyes and a manifold set and not a computer or smartphone.

[jimbojames]

Ah OK, I wasn't sure where the pressure was measured from. When it was regassed, the fill pressure went up to around 5 bar, so to me that meant still full of gas. I didn't mean that pressure meant it was fully working though. 

 

I'll check the shear plate on Saturday, my next available free time, but other than that, it'll be time for someone with the right equipment to check it over it seems. 

 

That's the problem these days, I'm more than capable of fixing most things (my day job) but haven't got the specific knowledge or equipment for everything! 

[J.R.]

For the cost of someone to check it over you could buy a set of guages and a vacuum pump if you can find  a source for the gas, it has expanded my knowledge.

 

The VAG system measures the high side pressure which equals the low side pressure when the system is not running.

 

The modulating valve can be replaced but you lose the gas unless you have the means to recover it.