95 LWB Overheating

[a1crisis]

95 LWB put on the road after storage for 3 years all fluids ( including antifreeze ) changed and ran with no problem 1 month. Recent heat wave in northeast and longer commute has caused temp gauge to start to move out of its usual dead center position to the high range after 15 minutes of running. At highway speeds of 70-75 temp drops to normal range. When I slow down for traffic or side roads temp starts to climb. Expansion tank shows no loss, hoses not leaking and neither very soft or hard. Fan has some resistance to moving when engine is hot but moves pretty easily. When temp climbs I put on the heat and blowers and temp drops instantly into normal range. Any direction would be helpful.

[57loboy]

I would suggest removing and flushing the radiator and double checking the viscous clutch. "Some" resistance may not be enough, though after sitting for 3 years and the recent fluid changes lead me to think goo got loose in the cooling system and is blocking the rad.