2007 Buick Lucerne Q&A

2007 Buick Lucerne Question: my 207 Lucerne overheats. Replaced thermostat, cooling fans, water pump

engine still overheats. The A/C stopped working too. Runs OK on the interstate roads but overheats in traffic -
Answer 1
I had the same issue and it was a plastic fin underneath that deflects the air upwards toward the radiator -