If the fan clutch is good it will have more resistance when it is hot than when it is cold. The difference will be noticable, just give it a shove in the counter clockwise direction. Hot, it should barely be able to get a blade width, cold it should get 2- 2 1/2 blade widths when you spin it.

Also take your water hose with nozzle on full blast and spray from the fan side of the rad outward ( toward front of car ). Really hose it down good. If you have the time or intrest pull back the shroud as best you can so you can get the hose in there good.

Mine was doing the same thing yours is and I did all the stuff you did but still got hot. After doing the hose down ( lots of black stuff came out when I did spray it out ), it hasn't heated up like that. I can sit in traffic, even with the air on and she barely gets above 9:00 even with the A/C on. On super hot days it gets a little warm if I run the A/C but if I roll down the windows and shut off the Air it cools back down. If all else fells try a new fan clutch or an aux fan ( this has a whole set extras you need to do to get it installed and working ) Oil change will keep it a little cooler also.

FCP Groton (fcpgroton.com) has quality volvo parts for excellent prices, with lots of selection on most parts.

Good Luck
Chip
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