Ford Mondeo III (2000 - 2007) - 2001 2.0 Aircon - Compressor on/off cycling

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Fri 16 May 2008 10:21
2001 2.0 Aircon - Compressor on/off cycling - M.M
Following a sucessful repair to my Mondeo aircon I just wondered about the design of a pump that cycles on/off frequently. I'd noticed mine do it and then read a comment in another thread about a Vauxhall that modern systems have this design.

What is the purpose of this as it would just seem to increase the chance of compressor clutch wear/faults??

David

Edited by Dynamic Dave on 16/05/2008 at 11:22

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Fri 16 May 2008 10:41
2001 2.0 Mondeo Aircon - Compressor on/off cycling - DP
My old mk2 TD used to do this as well. It drove me nuts, as the clutch engagement was so noisy and crude feeling. CLUNK, pause, tick, pause, CLUNK, pause etc. Hugely irritating at idle.

Cheers
DP
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Fri 16 May 2008 13:19
2001 2.0 Mondeo Aircon - Compressor on/off cycling - RichardW
You've got to control the amount of cooling the A/C is doing somehow. Cheap and nasty: Fixed displacement compressor, switch it in and out at full rate as required. Dearer and better: Variable displacement compressor, adjusting output to suit load. The VD requires a lot more moving parts in the compressor, and a more complex control scheme, but reduces the load on the compressor clutch. With multiplex wiring, and increasing installation of A/C in cars, the cost of the VD units has probably come down, so they're likely to be more common - and a lot more expensive to fix if / when they do go wrong though!
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Mon 19 May 2008 14:48
2001 2.0 Mondeo Aircon - Compressor on/off cycling - M.M
Richard,

Thanks. So my old Xantia would have had a pump that cycled too? Never noticed it but I suppose the diesel engine added to clicking and slurping hydraulics masked the aircon noise!

Things OK with you... bought a C5 yet?

David
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Mon 19 May 2008 17:28
2001 2.0 Mondeo Aircon - Compressor on/off cycling - RichardW
David,

Yes, the Xantia ones clicked in and out, but it was never very audible - it seems that some of the systems make much more noise than others.

I managed to avoid the C5 trap - I eventually found a nice condition 50k mile 2001X Xantia HDi 110 Forte Estate - dear at £3k mind.... still, clocked up 19k in the 9 months I've had it with barely a murmur - just had to wire a new feed to the blower relay, and re-seal the boot door lining. I presume that this car too will cut the A/C comp in and out, but I've never been aware of it....
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Tue 20 May 2008 08:26
2001 2.0 Mondeo Aircon - Compressor on/off cycling - M.M
>>>>I managed to avoid the C5 trap

Me too. I'd spent 9mths looking for the best Xantia TD Estate left in the country with no success, then 3mths casually looking at C5s but was very wary of the issues carried by many early ones.

Out of the blue this petrol Mondeo was offered by friends in the next village and I thought why not for a year or so and see how things go.

Missing the diesel performance already ... and the ride... very much missing the Xazntia ride!!

The good lady still has her TD Xsara Exclusive which continues giving perfect service... she wants a C4 next.

David
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