Mk4 (2021) White stuff on air conditioning pipe (?) around service port valve.

[Zeeb]

Is this normal? There is a white hard substance around what I think is the service port valve on the air conditioning pipe. It looks like powder but it is hard and doesn't easily scratch off.

I guess it is an aluminium oxide layer from the valve overflowing a bit (one year old car - not sure when it started). Is it normal for this to leak a bit in a new car as the air conditioning settles in?

There's also a blue marker line that someone might have drawn there - related?

[TomsFocus]

The valve shouldn't leak at all.  It's a simple valve that is pushed closed by the pressure of the gas beneath it.  Excess pressure can't allow it to leak.

I suspect it's 'blow back' from when the filler hose was released which wasn't wiped clean.  But it's definitely worth making sure it isn't leaking while still under warranty.

[Tizer]

I noticed mine was like that though not quite as bad after its 2 year service which was a year ago.

I've not had any problems since and will check it out again tomorrow when I give the car a service. I don't remember the blue line but I will have a look.

[Nimrodmk8]

I'll be checking mine at the weekend, just had it's 2 year service.

[RMurphy195]

Into the dealer under warranty, provide a printout stating what they are looking to fix, then make a record of the result. Example (redacted!) attached. Two objectives - get it fixed, if there's a problem, and/or get it on record in case of future disputes.

Example_Problems01.pdf

[Zeeb]

23 hours ago, TomsFocus said:

The valve shouldn't leak at all.  It's a simple valve that is pushed closed by the pressure of the gas beneath it.  Excess pressure can't allow it to leak.

I suspect it's 'blow back' from when the filler hose was released which wasn't wiped clean.

20 hours ago, Tizer said:

I noticed mine was like that though not quite as bad after its 2 year service which was a year ago.

Hmm, I just noticed under the black plastic cap - the rubber o-ring was bit out of place and there is a little yellow oily liquid in there. Not sure if the liquid is some kind of conditioner for the rubber ring - it doesn't seem to evaporate.

I tried turning the o-ring over, and once you screw the cap on, it bends up a bit whichever way it is in. (The valve on the other port sits flat and looks dry.)

I found a 12-page thread on another forum talking/arguing about the cap vs the valve in sealing the system:
https://hvac-talk.com/vbb/threads/176040-Schrader-Valve-or-Cap-What-s-the-seal

I haven't read it, but I guess the cap is more important than the cap on a tyre valve (ie, it is not just a dust cap), and that the metal 'Schrader' valve is the primary seal... so they are both important.

Anyway my 1-year service is in a week so I will get them to look at it.

 

11 hours ago, RMurphy195 said:

Into the dealer under warranty, provide a printout stating what they are looking to fix, then make a record of the result. Example (redacted!) attached. Two objectives - get it fixed, if there's a problem, and/or get it on record in case of future disputes.

Good idea. I have a bunch of stuff of stuff I would like them to do (nothing major) and it can't hurt to hand them a proper list even though I already filled in an online form with the other stuff.

[TomsFocus]

25 minutes ago, Zeeb said:

Hmm, I just noticed under the black plastic cap - the rubber o-ring was bit out of place and there is a little yellow oily liquid in there. 

Yellow liquid is PAG oil, mainly to lubricate the compressor, but does also keep the seals supple.

Sounds like you may have a seal fault though, hopefully it'll be sorted under warranty if so.

[Tizer]

I had a look at mine today and I also have that blue marker line in the same place but mine seems to be mostly below the white stuff, on your photo it looks like it is mostly above.

Mine has not become any worse over the last year and I took the cap off again and it is clean and dry with no signs of leakage or hissing sound. The rubber seal in my cap is in place and seems to be doing its job.

I read some of that link and there seems to be no definitive answer except that if the valve leaks then the cap should prevent most of the leakage coming out as well as keeping dirt away from the valve. The thread does seem to be more about industrial HVAC systems rather than small car ones. 

[Zeeb]

Ok, good to know the oil is normal.

I notice the rim of the port (low pressure I think) where the cap seals it - is thinner than the other port. That's why the rubber o-ring can tend to deform when the cap is tightened. In fact, once when I tried to tighten it a little more, the o-ring actually came off the cap and was stretched around the rim of the port - not the best design. (I only tightened it finger-tight; not especially hard.)

I think a lot of people will find the o-ring is deformed, unless there are different types of rubber rings. But it probably seals well enough anyway.

Maybe my port is sealed properly and it is just from overspill while filling or re-checking, as TomsFocus suggested (before or after being imported to Australia).

Interesting that Tizer has similar white powdery stuff as well as the blue marker line. Maybe the line is just to indicate it has been filled for the first time. Yes my marker line looks drawn partly over the top of the white stuff but it's hard to say - maybe it developed under the drawn line a bit.

Oh I see - that forum thread is not mainly about car air conditioners - so the plastic cap could have a diff function. It's possible in cars it is not needed to seal - but is just 1) a dust/dirt cap, and 2) used to do the 'hiss test' to show for a slow leak. With my old Nissan car, I would hear a small hiss when I took the cap off. I haven't heard hisses with my Focus caps.

I also read that at least some Fords don't use Schrader-type valves but a custom Ford valve.

Will update in about a week, thanks for the info.

[Zeeb]

In the service the mechanic wrote on my receipt - "Checked A/C pipe fault. Normal around weld of pipe. A/C working fine".

I didn't speak to the mechanic; the office assistant relayed this to me. Seems odd this would result from a weld (?) but I guess since some other people have the same it's not a problem.

When I take off the cap now, the o-ring comes out and sits stretched around the port, but it seems to seal with the cap on so I'll just check that it's on after services.

[Tizer]

Thanks for posting an update and you now have a record of bringing this up while still under warranty which might be useful in the future.

When I gave my car a service last week I took a good look at the other service port and there was a tiny bit of the same baked on white stuff near the valve. Personally I'm not that worried either.

[Nimrodmk8]

Mine had the white stuff on the pipe, I gather. nothing to much to worry about.