Ok i just got my non turbo 1988 mazda rx7. I start it it runs but after a while i turn on the vent and a grayish smoke blows out of the vents. It has no smell really. I think there is an oil leak but i dont think that is causing it. There is no smoke coming from the exhaust. Please help. Thanks

 

it might be the heater core

 

that happened to me in one of my old cars... turned out i just had alot of dust and dirt in the vents.

 

Ream the vents and tubes with a drier vent cleaner, vacuum as much of the duct work as possible, then wrap the drier vent tool in damp towels and ream them again.

 

You many have been blessed with a really good working R12 AC system.

Under the right conditions, I get condensed water vapor out the vents.



I hope it's not your heater core.

If you're running antifreeze in the coolant, you would smell it.

 

my old LTD used to blow frost out of the vents, that thing would freeze out anyone, only reason I bought the car from my friends grandmother

 

Is it steamy? My guess would be heater core, if it isn't steamy then maybe a small family of mice moved in a build a nest.