1999 Volvo D12B Clutch fan ON OFF consistently

I have 1999 Volvo D12b, the fan turn on off consistently. I change the selonode. Still same thing. No air leak outside. Don't know if inside there is something. Sometimes it starts working normal usually when bobtail or empty trailer.

Any help would be greatly appreciated.

 

Ac is off. The light on the Ac switch is off. I will disconnect Ac compressor power to see if that makes any difference.

 

I already changed one Ac inline switch which is by the windshield motor. There is another one beside condenser, I will change that tomorrow.

 

Radiator and air to air are new only 20k km on them. Had a radiator leak But this fan problem is been here before that.
Other test I did.
Last night I was idling 9 pm fan didn't turn on at all. May be once every 30 mins. By 1-2 am as it got colder outside fan start going on off every 30 sec.

Started driving 5.30 am. Fan turned off. Came on like once every 5 mins.

6.30 am started fueling fan was consisatly on for 20 mins. Didn't disengage for a second.
After fueling. Now I m driving at 98 km hr. Fan comes on every 30 sec. Sometime it doesn't come on for even 5 mins.

Other things I did. Jumped high pressure Ac switch with paperclip no difference. Tried disconnecting Ac compressor no difference. I did this when I stopped for fueling.

 

You mean if I have something front of my grill in cold months. No. No cover on the grill