1993 ford crown victoria exhaust leak
 

When I turn on the Fan the exhaust leak in on my 1993 Ford Crown Victoria comes through the AC Vents. Two years ago a mechanic ran a by-pass on my heater to keep from water flooding the front carpet because I could not afford the $1500.00 to replace the heater core. (You have to remove the dash to do this). Could I have a leak in the heater by-pass? Or, is there somewhere else I should consider.

It might be possible to reduce the fumes from coming into the cabin by keeping the function selector in the Recirc. position. That way it just recirculates the air inside the vehicle without pulling in any outside air. Exhaust fumes have a way of getting into the vehicle regardless and repairing the leak is the better thing to do.

Since exhaust leaks can be harmful even fatal if the concentration gets hi enough, it would smart and wise to have the exhaust leak repaired

Thanks Hanky, with an option of AC Max, AC Norm, Vent, Floor, Defrost/Floor and Defrost only I have no option of "Recirculation". on this 1993 Crown Vic. I do know what that is and my other car does have that. I thought it was the Vent at first but it comes on both Air positions as well. Getting too much for my commute to and from work so I will have to garage it until fixed. Thanks again Hanky. I appreciate your reply.

On just about all A/C systems AC Max is the same as Recirc. , try it !

Done it Hanky but still a strong odor of exhaust. I turn off the AC and it goes away.

This is only speculation, but if the exhaust fumes are collecting under the hood and the heater tubes are open and were leaking, the fumes might be getting sucked in through there. What if you capped or plugged the tubes on the heater core that had the hoses connected to them ?
This is a far out thought, but sometimes you need to play detective. Let us know if that solves the problem.
By the way exactly what was leaking exhaust fumes, if your mech told you ?

My reply is not so "quick" Hanky but I have been a little busy with work, doctors and not so good mech's. I am $480 poorer and still have the leak. Tried the capping of the tubes from the heater core by-pass that was done and still get some exhaust but not as often. Will just have to live with it I guess. Now I have to look for some parts for my Crown Vic as well. I appreciate you hanging in there for me Hanky and tried every offer. Take care and thanks again.