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Please play nicely.  No one wants to listen/read a keyboard warriors rants....

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Author Topic: fuel consumption  (Read 2280 times)

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Andy B

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Re: fuel consumption
« Reply #15 on: 11 January 2008, 16:34:23 »

Quote
Just thinking that the system may just need a regas. do you get a jump in the rpm with the c/c is swiched on?.  

Mmm! I think you're correct. The revs do rise & fall as expected but ...
a rise in revs isn't a difinative answer to whether the A/C compressor is clutching in. At some time in the past, before I got the car, the electrics to the A/C have been played with. There's an earth/ground/0 volts/whatever you want to call it  ;) under the battery that had been fiddled with. So, as you do I put it back to how it Vx had originally intended - the A/C packed ie the compressor didn't clutch in although there was a rise & fall in the revs when you put the A/C on or off. When I put the wiring back as was the A/C worked. The revs are obvioulsy not requested by a pressure rise or fall in the refrigerant lines.
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Kevin Wood

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Re: fuel consumption
« Reply #16 on: 11 January 2008, 16:40:30 »

The signal to the air con compressor clutch passes through the engine ECU, IIRC, so the engine ECU can veto the use of air conditioning (if coolant temp is too high, for example). If there is a break in the circuit further on in the system, ECU will see that air con is on, thus raising idle speed, but clutch won't engage.

There are manual pressure and temperature sensors which can disable air con compressor. Definitive way to tell if it's running is to watch the compressor pulley. If the front of the pulley with the 3 round weights on is spinning, it's running.

Kevin
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Andy B

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Re: fuel consumption
« Reply #17 on: 11 January 2008, 17:05:40 »

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...... There are manual pressure and temperature sensors which can disable air con compressor. Definitive way to tell if it's running is to watch the compressor pulley. If the front of the pulley with the 3 round weights on is spinning, it's running.

Kevin

That's how I realised the A/C had stopped working after I'd 'corrected' the wiring. It's to dark outside now, I'll look tomorrow. there's a good A/C specialist just up the road. I'll take it too him as the system hasn't had anything done to it while I've had the car [size=8](apart from a can of R134a last summer :-/)[/size]
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