406 Diesel Idle speed

[Peter (archive)]

What is the most common cause not to drop to normal idle speed on a warm engine (XUD9TE)? It keeps on running on fast idle, even with hot engine, with or without airco switched on.

Things I checked:
Vacuum hoses - OK
Temp sensors (3 in total in the thermostat housing) - OK Diaphragm and cable - OK Idle and fast idle setting screws - OK

BTW, the airco only works on revs higher than idle. Do these two things have a link?
Thanks.

 

[CoyoteBoy]

Temp sensor connection to the ECU gone dicky?

Normally the aircon would up the idle itself though.

J

 

[Peter (archive)]

Temp sensor connection to the ECU gone dicky?Must be the cable on the green connector on the thermostat housing, right?
And is this a common problem?

Normally the aircon would up the idle itself though.

That of the aircon is right. But also with it switched off, the speed doesn't drop. Is it likely that they are linked to eachother?