Ok, you have everything covered and the cold weather might be a factor here.
The idling is not generating too much heat into the cooling system and the external cold is sufficient to cool the coolant in the radiator resulting in the fans not working.
I would suggest a simple test to find out if the fans would work by increasing the temperature. Start engine and let it reach operating temperature. Should take about 10 to 15 mins. Rev engine to 3,000 rpm and hold till any of the following occurs:
1. Fan starts working
2. Temperature gauge goes up to more than 3/4.
Let me know the results.
Sunday, February 1st, 2009 AT 12:37 PM