make shure your coolant level is ok, the compressor draws some horse power when it kicks in; it might run warmer when u set still in traffic ,make shure your truck isnt hot , theres a fluid level indicator on your radiator resivor,check it . make shure engine is cool!!! take radiator cap off make shure you have proper amount of fluid in each. make shure your fan on your radiator is working . that cools the engine.
