Cusser
+1y
At idle (1) your rpm are lower (2) there's no ram effect of air being forced through the condenser (in front of the radiator), so not so abnormal. I suspect that you need a new fan clutch to improve the air flow over the condenser; I've replaced that about every 6 years on my 1988 B2200 (Arizona desert). Also make sure all of your fan blade shrouding is present.
If you want to try to test out the fan clutch, Google such information.