Another AirCon query: hissing noise

[OldGreyBeard]

Hi

 

I have a 3-yr old 140CR 2.0 dsg 4x4 that has been more or less faultless and is now out of warranty. I rarely use the aircon, living in the NW of England, but I turned it on a day or so ago and there was a significant hissing noise coming from the vents. Is this somehting to worry about and, if so, is it best to take it to the Skoda dealer to to an aircon specialist? The aircon seemed to work OK apart from the noise.

 

Thanks

[KenONeill]

Well, I live even further North and leave my Climate in automatic all the time except when I want demist. Climate at least dehumidifies and gives you a demanded temperature, not just "cold".

 

In any event, if you do have manual air, it's better for the system to use it at least once a month to stop the seals drying out. Which gets us back to possible problems. I can't diagnose from here, but I'd suspect:-

1. Loss of gas mass from natural aging.
2. Possible leakage at seals that aren't being lubricated.

An AC specialist will diagnose, or you could go to Kwik-Fit, who won't charge if your air isn't colder after their automatic machine has done its stuff.

[voluptua]

A technical question:  The air con pump goes round all the time, because it's belt driven.  So what is the action of turning on or off?  Is there an inner clutch that disengages the pump, or a valved by-pass that sends the fluid round in a loop?  Or something else?

[137699]

Hissing is never a good sign where AC is concerned. Means the system is low on gas usually.

Don't take to Kwik Fit -take to an AC specialist.

 

But have a good look at your condenser first - fair chance it is holed due to stone damage.

If it is, then Skoda *should* replace it for free as it's a known design flaw and the new condensers (post 2013) have a different design to prevent this recurring.

[Ryeman]

A technical question:  The air con pump goes round all the time, because it's belt driven.  So what is the action of turning on or off?  Is there an inner clutch that disengages the pump, or a valved by-pass that sends the fluid round in a loop?  Or something else?

It's always been due to a clutch engagement (magnetic, I seem to recall) activated by a thermostat from your temp setting.

[voluptua]

Thank you. That makes sense.

[freedie]

That hissing noise you hear means that you need to regas the a/c system ~ nothing to worry about if done soon.

[Ryeman]

If you can hear the gas escaping, I would have thought it would be empty o/night.

[freedie]

[muddyboots]

My Focus AC always used to hiss whenever the car was standing still.

Traced it down to the fact the AC fan was faulty, so at standstill there wasn't enough airflow over the AC condensor. The AC would hiss for a while, then you'd hear the click as it cut out. Then it would click as it switched on again, hiss for a bit, click off again, repeatedly while you were stood still.

Once on the move, it was fine.

The hiss wasn't escaping gas.

[137699]

Hissing sound isn't gas escaping, it's a low pressure noise for the remaining gas finding its way around the system.

[bw10030]

Yes, and dealers aren't the best - my wifes has just had an 'aircon service', it was perfect when it went in, now hissing like an angry snake!!! Back to the dealer for me. NOT HAPPY!!!!!

[137699]

If it was perfect, why did you get it serviced???

[Ryeman]

Yes, and dealers aren't the best - my wifes has just had an 'aircon service', it was perfect when it went in, now hissing like an angry snake!!! Back to the dealer for me. NOT HAPPY!!!!!

Could it be another gender issue?

I'd like to know to what extent the lubricant degrades in a sealed environment and what schedule should apply for a service - or is a simple case of 'on condition'?

[OldGreyBeard]

Thanks for the comments. The aircon packed up completely last week so I took it to the local Skoda dealer (David Ian in Morecambe). As might be expected, they declared the condenser to be leaking. They seemed to take a long time to come up with a price for fixing this, which turned out to be because they were contacting Skoda to see what contribution they'd make to sorting it out. In the end I have a price of about £100 for the job, which doesn't seem too bad to me.

 

Car is a 140 TDI DSG and first registerred in November 2011.

[bw10030]

It was 'due' a service, and was getting a little smelly. Had a new compressor and condenser fitted - still faulty (very noisy, needed another compressor apaparently. Sold the car . . . . !!!

[Yeti1110]

Hissing is never a good sign where AC is concerned. Means the system is low on gas usually.

Don't take to Kwik Fit -take to an AC specialist.

 

But have a good look at your condenser first - fair chance it is holed due to stone damage.

If it is, then Skoda *should* replace it for free as it's a known design flaw and the new condensers (post 2013) have a different design to prevent this recurring.

My 2010 Yeti is making exactly this same hissing noise. Where is this a/c condenser? Happy to check it myself if I knew what it looked like....

[Breezy_Pete]

It's the large radiator-like thing in front of your coolant radiator.

I doubt that you'll find that damage to it leads to hissing noises when the AC is on.  Reason being that anything but the tiniest leak will lose all of the refrigerant fast; once the refrigerant is gone, the system's sensors will not let the AC be switched on. If yours is switching on and doing something (cooling-wise) then it must have some refrigerant remaining, and therefore can't have a catastrophic leak. Slight leakage (at joints/seals) is normal however, and if yours is a bit leakier than average, you've probably got down to a level where it needs re-gassing.