Date: Sun, 02 Sep 2007 16:55:43 +0100 From: Colin Stamp <col.dustbinnospamp.plus.com> Subject: Re: [XP] Sporadic aircon
On Sun, 02 Sep 2007 09:39:37 -0400, Steve B. <nonenospam.com> wrote: >On Sun, 02 Sep 2007 10:56:52 GMT, "Mrcheerful" <nbkm57nospamail.com> >wrote: > >> >>"Colin Stamp" <col.dustbinnospamp.plus.com> wrote in message >>news:td3ld35g32isos1ag912fl96ktfaf9dcs7nospamcom... >>> On Sun, 2 Sep 2007 09:38:51 +0100, "moray" >>> <mtb_hyphen_rulesnospamail.co.uk> wrote: >>>> >>>>Most likely a knackered clutch on the compressor. >>>>Connect a test lamp from the clutch power wires on the compressor, and see >>>>if it's still getting power when the system stops working. >>>> >>> >>> Could be. The next part of my cunning plan is to check the clutch is >>> pulling current. >>> >>> I'm still wondering if there might be a refrigeration problem which >>> could cause the high-side pressure to intermittently drop to a >>> "switched off" level even with the compressor running though. >>> >>> Cheers, >>> >>> Colin. >> >>moisture in the system can cause this, it freezes to form a plug, then melts >>etc. >> > >But when you get a blockage in the system high pressure goes through >the roof and low pressure drops very low (or even to vacuum if the >switch doesn't cut the compressor off). His pressure is going back to >an "at rest" pressure. > >You need to know if the compressor is turning or not when the problem >happens. The LED is a good idea but an LED will light with virtually >no current. A compressor clutch needs a few amps to pull it in. If >you have a poor connection / bad switch somewhere in the loop it is >possible for there to still be enough oommmppf to light an LED and not >pull in the compressor. Kind of like having a dead battery... The >interior lights will still come on but the starter won't spin. > > Steve B. I have news!. It's the clutch for certain. I finally managed to get the thing to fail whilst parked today, by letting it idle for ages on the drive after a longish run. It stayed failed when I opened the bonnet too, so I could finally check stuff out properly. The compressor isn't turning even though there's 15mV across its fuse, which is the same voltage as when the syetem works properly and the compressor is on. So the clutch is definitely pulling normal current, but it isn't engaged. Right. Now I need to fix the bloody thing. A quick Google suggests that I might be able to fix it by taking some shims out to compensate for the wear. I suppose the next step is to take the clutch apart and see if that's possible. Anyone done this on a 9-3 before? Cheers, Colin.
