what could this be?

Question

My boss just called me for advice. Apparently, an employee was driving the company vehicle (a 96 Ford 150van, 4.9L w/ 300k miles), when the employee heard a "pop", and smoke started coming in through the vents.
I can also tell you that the van had developed a "miss" yesterday, like it had dropped a cylinder. I was planning on checking the plugs/wires/distributor today- before this happened.
Any relation btwn the two?

Just talked to the employee. He described the smell as "kinda like garden weeds".

Answer 1

Smoke from the A/C vents could be several things - depending on what kind of smoke. It could be an electrical problem (with the smell of burning wires/plastic). It could also be a blown A/C evaporater coil ( which may or may not have a musty smell caused by the leaking oil in the system). Or, it could have blown the heater core, which would smell like anti-freeze. So, my first question would be - what did it smell like? If there was little or NO smell, my guess would be the evaporater - which would should be easy to validate, as your airconditioner won't cool anymore. Now, if the smoke came from the engine hood vents - outside the vehicle - that's a whole different story --- and would require a lot more info.

Answer 2

what did the smoke smell like. What you describe 'pop' then smoke coming through the air vents. soudns like a shorted wire behind the dash board. The only othe rplace where the air vents open up to teh engine is in the heating coil.but if that blue then you would be gettign steam.

Answer 3

If smoke came through the vents you had a electrical fire.
The chances of a tune-up being related to smoke going through the vents is slim to none.

Answer 4

souds like you could of possibly popped your evap core, if it was electical fire you would know it. see if the ac works still. other than that have a tech check it out. could be dangerous if it is electircal.

Answer 5

sounds like it needs a motor