www.jec.org.uk

Having just about replaced very bit of the aircon system, including the evaporator and compressor and then at last in 2020 having blissfully cool air wafting across the cabin once more - this season the gremlins have decided to initiate an oscillating blower on speed 1 (can't detect the same on position 2 & 3 and then to add to the woes of this sad XJS owner - after a good 20 mile run yesterday the whole darn system refused to switch off and kept running with the ignition off and key out! By experimenting I managed to get it to turn off by putting fan speed to "off" and starting the engine again and then everything switched off.........

Life is nothing if not unpredictable when it comes to air conditioning in these beauties!

Any ideas out there? all hints and tips gratefully received

Deep joy

smudge56,

Those symptoms are indicative of a failed Darlington resistor.

The pulsing noise sometimes happens when the Speed is set to 0. That's often matched by one blower side running at Speed 2 when the setting is on 1. And the fans running with the ignition off is indicative of a permanent live caused by the fail of the Darlington transistor.

There's lots of posts on various internet forums on replacing the transistor. There are commercial products available from places like Maplins etc. to replace the component. I THINK it's a DN6284.

Good luck

Paul

Thanks Paul will let you know how it goes....

Maplin are, of course, no longer on the high street. I've found cpc.farnell.com and uk.rs-online.com useful.