does anyone know what the internal pressure should be on the aircon system. I've recently changed the condensor, compressor for new ones and a re-gas. Since all the work has been done, the aircon works but. I'm getting a high pitched air/ metalic noise inside the cabin that can't be heard from outside the car. I did think it was the interior fan but is not that. Does anyone have any ideas as to what the fault is before I call the local aircon guy on Monday.

5 bar low side 5 bar high side with the engine off is a general pressure it's affected by temperature and altitude. 10 bar high side engine running ac on is the general pressure and 2 bar low side ac on is the general pressure. These can obviously be correct and your ac can still not be working so remember that you need density so having the correct weight of r134a is required a mk2 Octavia should be about 0.525 grams + or - 0.025 grams.

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Also why was the compressor replaced?

Edited 18 July, 201510 yr by FLAPPERJACK7

Don't think my pressure has ever been as high as 10 bar, that's using the climate system to check.

Did your old compressor seize? Or the drive bolt problem?

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It was the Delphi unit with the drive bolt problem. The bolt never moved any more in a year, but as I was doing a 2000 ish mile round trip to France I wasn't taking any chances.

Can you record it and put it on here I will have a listen if you can.

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Can you record it and put it on here I will have a listen if you can.

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I could give that a try, failing that I could email it to you. Will probably be a couple of days before I can do this.