Aircon not working diagnosis

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
Mɐʇʇ
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Re: Aircon not working diagnosis

Post by Mɐʇʇ » Tue Jun 29, 2021 12:47 pm

Well it all looks professional. No idea what I’m doing though. :mrgreen:
The high pressure side starts at >150psi or so and then drops once it's got going and the air is cold.

I suspect I’ll be buying a vacuum pump soon, just because...
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Shoppinit
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Re: Aircon not working diagnosis

Post by Shoppinit » Tue Jun 29, 2021 1:18 pm

High side seems a bit low. What are your static pressures (engine off and cold)?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Aircon not working diagnosis

Post by Mɐʇʇ » Tue Jun 29, 2021 1:31 pm

Yeah, it started higher and then dropped. It does pump out proper cold air though - so something is working.
I thought I took a pic of the pressure engine off & all cold - but fat fingers. Will have another go.
"not a professional engineer, mechanic and mechanist"

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Shoppinit
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Re: Aircon not working diagnosis

Post by Shoppinit » Tue Jun 29, 2021 2:38 pm

Mɐʇʇ wrote:
Tue Jun 29, 2021 12:47 pm
The high pressure side starts at >150psi or so and then drops once it's got going and the air is cold.
This is with AC set to max cold, right?

Mɐʇʇ wrote:
Tue Jun 29, 2021 12:47 pm
I suspect I’ll be buying a vacuum pump soon, just because...
You'd need a gas recovery system, too, if you intend to do any work on the system. And a way to accurately measure the amount of gas (and PAG oil) to go back in.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Mɐʇʇ
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Re: Aircon not working diagnosis

Post by Mɐʇʇ » Tue Jun 29, 2021 2:42 pm

I thought it was just a good set of scales to measure gas going back in?

Anyway, I should stop this line of thought. I have enough tools in the garage as it is....if it's broken, I'll fix it and then get kwikfit or whoever to vacuum & recharge it with the machine.

Which reminds me of the fix on my old Saab. The high pressure line had corroded through from before we bought it. So I rigged up an adaptor to the compressor to pressurise it and find the leak. Then a bit of JB Weld, couple of hose clamps and a bit of tube that fit snugly round the outside to make a patch and bingo - aircon fixed without having to take the whole front of the car off, not even the bumper, to get working aircon again.
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Shoppinit
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Re: Aircon not working diagnosis

Post by Shoppinit » Tue Jun 29, 2021 2:49 pm

Brilliant. I am pretty sure this is what has happened to my 9000, a lot of corrosion around the high pressure switch. Anyway, it all looks far too corroded to try and fix. Suspect I am going to let the car go after the next MOT anyway.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Aircon not working diagnosis

Post by Mɐʇʇ » Tue Jun 29, 2021 6:40 pm

Engine off and cold.
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Re: Aircon not working diagnosis

Post by Shoppinit » Tue Jun 29, 2021 6:54 pm

Looks about right. But there’s only so much you can tell from the pressures.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Mɐʇʇ
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Posts: 2680
Joined: Tue Oct 07, 2014 8:30 pm

Re: Aircon not working diagnosis

Post by Mɐʇʇ » Tue Jun 29, 2021 6:57 pm

Thank you.
"not a professional engineer, mechanic and mechanist"

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