1.9td 1998 aircon pump clutch

wotsupnow · Post by **wotsupnow** » 13 Aug 2004, 04:21

Doesn't engage until engine is above about 1200rpm, is this normal or a fault ? It's really annoying, cruise along the motorway lovely and cool , stop in town and it starts blowing moist warm air again, sit holding the throttle at 1500 rpm and its cool but you look a prat.
I've watched the pump form under the wing, at idle it stays out, rev up and it starts spinning.
Pete

np · Post by np » 13 Aug 2004, 04:49

Mine works at 800 ish rpm at idle constant.Sounds like a fault,need more expert help/

alan s · Post by **alan s** » 13 Aug 2004, 05:31

That's not right.
I can't speak for these later types but earlier ones worked on an electromagnet snapping in a clutch and the thermostat fed or cut off power to the clutch as it was needed to keep running or stop the compressor. These would work down so slow that they could be turned by hand, so on the assumption that it's not just the belt slipping, you've got either a power problem due to typical froggy wiring or a slipping or worn clutch.
If it's just wiring not getting the power through, it's a DIY but failing that better go see the local air/con man.
Alan S

tomsheppard · Post by **tomsheppard** » 13 Aug 2004, 13:42

I'd second that. The clutch draws about 5 Amps and is intolerant of voltage drop in corroded connectors. Clean them up and ensure they are tight, like the drivebelt as Alan says before panicking. Any oil (from the engine) around the clutch may suggest slippage in which case you can spray the clutch with a tin of brake cleaner.

Mosser · Post by **Mosser** » 13 Aug 2004, 14:54

I think that the aircon compressor might be controlled by a small black box called a bitron unit, on my 406 it was located under the front left wheelarch liner and as Alan and Tom said, it is probably down to corroded connectors, on mine, the corrosion was so bad that when i unplugged the connector most of the pins stayed in the connector socket!!, and as these Bitron controllers are about £70 and my connector was heavily corroded i decided to cut off the connector and solder all the wires direct onto the bitron, I used uncured silicone sealant to waterproof all my handywork and provide some strain relief on the wires afterwards

tomsheppard · Post by **tomsheppard** » 13 Aug 2004, 18:44

Nice dodge, Mosser. I've recently stripped a Bitron box and I can confirm that you cannot fix them if the tronics go down. THe parts within are custom programmed devices, alas.

wotsupnow · Post by **wotsupnow** » 15 Aug 2004, 17:04

The 12v supply to pin 4 of the Bitron is 10v and rises when the engine is revved, the fuse feeding it has 12v either side so there must be a corroded connection along the way.....
Anyone know how to get behind the fuse box near the drivers seat under the dash ? the last time I had this voltage problem it was the connectors on the back of the fuse panel on an Austin A40 ! That had 12v supply to the sidelight switch but it would drop to 0v when you turned them on.
Where does the harness run through the bulkhead? is there a connector in there too ? the inner wing connectors are fine.
Pete