Exhaust smoke is coming in through the vents on the inside of the truck.
Hi. First thing to note is you should not be getting exhaust gases into the cab through the a/c vents unless you have an engine that is leaking exhaust. My recommendation is to have your engine checked for exhaust leaks, focusing at the engine exhaust manifolds. If you continue to see smoke coming out of your vents, then it is most likely coming from the heater core that is leaking coolant causing smoke to emerge. My recommendation is to have a mechanic come to you, like one from YourMechanic, to inspect and diagnose your problem.
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