Group:
I have had this problem on and off for six months.
Temp sensor and fan relay have been changed six months ago and seemed to cure the problem. But now it is back again.

When fan is running, I can only shut it off by pulling the fuse.
I had the problem on Monday and took it to the experienced Volvo technician.
When I got there and put the fuse in, the problem was gone.
He said there was a code set for low fan speed.

When the engine is running the fan speed is high.
When the engine is shut off, the fan goes to low speed for 5 minutes, then shuts off. If I put the key back in and turn it on, not start, the fan comes on at high speed. Remove key and fan goes to low speed for 5 minutes.

If I pull the fuse while the engine is off and the fan is running, then the fan stops. Put the fuse back in and fan starts again.

On Wed, the CE light came on with no fan problem.
On Thursday (today) short drive from cold on a 45 degree day, no A/C or anti-fog usage, the same problem started all over again.

I think it is clear that the relay is doing everything it should.
I know the A/C system pressure is involved, but I do not know what sort of fault would turn the fan on as described.
Would an open circuit (high resistance) at the sensor turn on the fan?
Or would a short somewhere do it?
I cannot even see the temp sensor under the thermostat, much less measure it.

Is there a connector where all the signals come together so I or technician could measure things when the fan is on in error?
I am convinced that it is a sensor or connection problem, with the connection being the most likely.

Who can shed light on what the problem might ve or where to look?

Thanks,
sixvolvos