outside air and smells getting into the cab.

No, other than putting a plastic bag on your head. Not a good option either.

 

I been reading all, I understand that the cabin is not completely sealed but, in reference I have a problem a very strong smell of exhaust comes in to the cabin only when i turn on the heater, but this only happens when I turn on the heater, unlike when i turn on the a/c. no smell nothing. where do y'all thing is the problem??

 

If it is coming in with the heater it is likewise coming in with the A/C, the air comes in the same location for both A/C and Heat. I am assuming you are in RECIRC Mode when using heat and A/C.

 

the smell drops down if i do not recycle, it gets worse if i recycle, but if I turn the A/C no smell in difference if I recycle or not

 

You shouldn't smell exhaust and have an exhaust leak somewhere. Carbon monoxide is nothing to screw around with so take it to a mechanic that has an emissions check wand. They can pass it the length of your exhaust and find the leak.

 

I guess. thank you..I'll head out to do just that. need it to renew the entire exhaust piping..