air con noises

[shagmeister]

As i stand before the place of all knowledge i wonder if you can all help me again.  my 150 pd has developed a strange noise.  After a long run with the aircon on and i load or unload the aircon system it makes a grumbling noise, like a large fan running on.  i have throu a long process of elimination established its not a fan but it is definately aircon linked, any ideas?  ta in advance shagmeister

[red16v]

I am no expert but I suspect the 'grumbling' noise is the air-con compressor - much like the noise you get from a household fridge (and after all air-con is just a fridge with a blower behind it) I would n't think it a problem unless it was particularly loud ? If the air-con system wasn't working then the most likely cause would be a loss of compressor fluid or pressure within the system - this can be topped up by your local dealer. (You would know if it wasn't working because you wouldn't get any really cold air and wouldn't be able to get the internal temperature down inside the car). regards, yt.

[S11EPS]

I've got exactly the same noise on my PD150, does it most after a long run and switching the engine off, the thing will grumble for anything up to thirty seconds.

The same noise can sometimes be induced by switching the air con off (but still have the fans running) when sat in traffic.

I always forget to mention it to the dealers when it goes in fo service, but likewise, they've never picked it up as a problem.

Mine has been doing it for well over a year now, the air con is still icy cold, so I don't think its in any way detrimental to the performance

[red16v]

As you say, I don't think it's a problem providing you are still getting lots of cold air when you need it -

On a related note, down by the passenger footwell on what would be the 'transmission tunnel' on a rear wheel drive vehicle is a small grille. (there is not one on the corresponding drivers side) - do you know what this is for ? even with the air-con going 'full blast' nothing ever seems to come out of this 'grille' ? I'm wondering if it perhaps linked with providing some sort of air pressure equalisation - perhaps when the system is using re-circulated air rather than external air ? any thoughts/knowledge welcome. Regards, yt.