A/C re-gassed again.

[AMGeed]

I found out last weekend when we had that warm weather that my S204 a/c is again blowing only warm air, despite being checked for leaks last year and re-gassed.
Fearing a holed condenser or duff compressor I got a mobile A/C guy round this morning to see what the problem was.
He emptied the system (almost empty of refrigerant) and put the system on an air test which held steady for 15 minutes without losing a single psi.
He was happy there were no leaks and refilled the system with R134a and added a little oil for £65 and left with the A/C blowing ice cold as it should.

I'll wait to see how long it blows cold, but I'm convinced something isn't right. I also had to use an a/c anti bacterial bomb as it had a pretty nasty smell after re-gassing.
Surely both a/c specialists can't be wrong about a leak?

 

[rf065]

I had a Ford Ranger regassed 4 times over a 6 month period, I was continually assured there was no leak until the very last time when they found a leak in the condenser and replaced it.
Only then, was it fixed.

 

[AMGeed]

I had a Ford Ranger regassed 4 times over a 6 month period, I was continually assured there was no leak until the very last time when they found a leak in the condenser and replaced it.
Only then, was it fixed.

I wonder why the leak , if there is one, isn't showing with an air pressure test?
Does it require an UV dye test?

 

[rf065]

I wonder why the leak , if there is one, isn't showing with an air pressure test?
Does it require an UV dye test?

Not sure many actually test with air pressure, usually they use a vacuum test which can mask a leak.
Most annoying when you insist the system is leaking, yet they say no and regass it anyway, even though regassing a system with a leak is an offence.

 

[Muckypaps]

In all fairness, 15 mins is not a long time.
it might lose 1psi in 6 hours, then you’re looking at 4 per day.
So in 30 days you will be empty again.
They haven’t got the time to leave the gauge on for a long period.
If nothing has been changed, you know it’s going to happen again.

 

[st13phil]

Not sure many actually test with air pressure, usually they use a vacuum test which can mask a leak.

^ This.

The gas doesn’t just disappear, there has to be a leak I’m afraid, Roger. The system really needs to be pressurised with a dye to determine where the leak is.

 

[Stratman]

Is there dye in the system? Buy a UV torch off ebay and have a look under the bonnet. Favourite places for leaks are where the pipes enter the condenser (dissimilar metal corrosion) and the condenser itself. Condenser leaks can be tiny, smaller than a pinprick and will only leave a small amount of dye behind, it needs careful inspection.

 

[AMGeed]

No dye in the system to my knowledge.
If and when it starts blowing warm again I'll insist on a vacuum test and a dye test after if nothing shows up.
As said, the gas is going somewhere. Its a sealed system.

 

[st13phil]

If and when it starts blowing warm again I'll insist on a vacuum test and a dye test after if nothing shows up.

The problem with vacuum testing the integrity of an a/c system is that very minor leaks that take weeks for the system to de-gas to the extent that you notice it’s not working just don’t show up. Pressurising the system is more reliable in finding if the system does or doesn’t have a leak, but running it with dye in the system is the best way to actually find the leak unless it’s a big one.

Sometimes slow leaks show up by leaving an oily deposit around them that tends to attract dirt. Have you had a good look around the condenser and the unions for any signs?

 

[m80]

I ask ATS to carry out a nitrogen pressure test. Too often the machine on vacuum test has been pointless.

 

[Farmer boy]

My wife’s Fiat 500 needed degassing after 10 months so asked for a test ATS said all fine but said LP filler cap was missing for some reason. Degassed and all fine. They did not have a cap to cover the port so I searched the web for one. I zip tied a finger of a rubber glove over the port while I awaited the cap arriving the finger inflates showing the valve was not sealing. The valve is similar to the ones used on a push bike. New valve core fitted using a flit from EBay so no gas escapes then swapping the core. Car fine over a year on. Begs the question why fast fit garages insist on new valve core for road tyres but don’t change them on air can especially as the valves may not have moved since the cars production several years earlier.

 

[alabbasi]

You probably turn your ac off during the winter which causes the seals to dry out and the system to leak. But think about the 50 pence you saved at the pump.

 

[AMGeed]

You probably turn your ac off during the winter which causes the seals to dry out and the system to leak. But think about the 50 pence you saved at the pump.

I know all about the seals drying out through lack of use. I continue to run the a/c during the winter months.

 

[alabbasi]

In that case, soapy water and pressure test it instead of vacuum.

 

[geoffus]

I know all about the seals drying out through lack of use. I continue to run the a/c during the winter months.

Is that a true story about seals drying out, I read somewhere that it was untrue, the lubricant in the system will keep everything lubricated even if its not running ?
Has anyone every had seal failure, or was it simply a leaky pipe or condenser.

 

[rf065]

Is that a true story about seals drying out, I read somewhere that it was untrue, the lubricant in the system will keep everything lubricated even if its not running ?
Has anyone every had seal failure, or was it simply a leaky pipe or condenser.

You don't usually see anyone complaining about seal failure, you just get complaints from people who rarely use the air con that it's not working anymore.
And you've guessed it, because all the seals have dried out and the system cannot hold any pressure anymore. It is a real thing!

 

[geoffus]

You don't usually see anyone complaining about seal failure, you just get complaints from people who rarely use the air con that it's not working anymore.
And you've guessed it, because all the seals have dried out and the system cannot hold any pressure anymore. It is a real thing!

So a dye would show up around the compressor if any rubber seals had dried out ?

 

[rf065]

So a dye would show up around the compressor if any rubber seals had dried out ?

I've heard many cases where even with a UV dye, the leak has not been obvious. Some of these leaks are so small they are a nightmare to pinpoint, and most of the air con outfits are more interested in a quick turnaround than spending hours looking for something. Much easier to spend 10 minutes and say it's fine, regass it and take the money.

 

[geoffus]

Mine needs a re-gas, so will have it done soon and hopefully they will put some dye in, I have a very strong UV light so will keep an eye on any suspect leaks.

 

[alabbasi]

Yes, the lubrication happens when the pump runs. It's not just air con systems, seals dry out all the time