Vintage AC Smells Like EXhaust

[badmonza]

Instantly when you turn it on it smells and burns your eyes. I have checked for exhaust leaks and found none. Has three inch exhaust out the back of the Nova. LS3 making about 575 hp at flywheel. Has the breather top catch can coming off both valve covers and the filter has been relocated under the car to the rear. I have checked the firewall and under car for openings to let air in the car and none. Anyone have issues like this? Wife will not ride in the Nova cause it stinks so bad.

Thanks

[dhutton]

Pinhole heater core leak spraying antifreeze?

Is the heater control valve installed in the correct line?

[Vimes]

New system or in there a while?
Smell when the fan comes on without the AC on or only when the AC is on?
Instead of an exhaust smell, might it be a burning wire?
Smell at all speed settings or have you only tried high?

Aside from the possible antifreeze smell which to me smells sweetish if using the green stuff, or kinda moldy sweet with some of the others, it sounds to me like it might be a burning wire, or possibly the speed control resistor. The motor for the blower might also be going out, but I'd think that would be unusually noisy too.

The possibility of a shorted wire would be a HUGE concern to me. That can set the car on fire. I'd run the wiring from the fan to the controls, and perhaps through the firewall to the compressor and high pressure switch paying close attention to the pass through.

[badmonza]

It cools good and smells at all speeds.

[Vimes]

If you can, feel the fan motor while it's running. It should be slightly warm to the touch. If it's too hot to touch, there's the problem. I'd also inspect the wiring for shorts against something sharp under the dash, likely the main power wire to the fan. It doesn't have to be a place where it's pulled tight either, it can be somewhere that the wire is able to move back and forth against something sharp but not necessarily against it when the car is parked. Since it's all fan speeds that would rule the speed resistor out. Assuming you only smell the problem when the ac is on, not when it's turned off, which would put the problem between the switch and wire. Oh, and feel the switch when you're smelling it, it is possible to have a high resistance point inside the switch or the circuit board to which it is attached. The switch should not be hot at all, but i may need to run for a few minutes to get heat out to where you can feel it.

[dhutton]

If you can, feel the fan motor while it's running. It should be slightly warm to the touch. If it's too hot to touch, there's the problem. I'd also inspect the wiring for shorts against something sharp under the dash, likely the main power wire to the fan. It doesn't have to be a place where it's pulled tight either, it can be somewhere that the wire is able to move back and forth against something sharp but not necessarily against it when the car is parked. Since it's all fan speeds that would rule the speed resistor out. Assuming you only smell the problem when the ac is on, not when it's turned off, which would put the problem between the switch and wire. Oh, and feel the switch when you're smelling it, it is possible to have a high resistance point inside the switch or the circuit board to which it is attached. The switch should not be hot at all, but i may need to run for a few minutes to get heat out to where you can feel it.

Vintage Air switches do not pass significant current so it’s highly unlikely they would get hot. Similarly they don’t use resistors to set fan speed.

[Vimes]

Vintage Air switches do not pass significant current so it’s highly unlikely they would get hot. Similarly they don’t use resistors to set fan speed.

I've not actually installed one yet (on my list, mine's on a shelf) so was drawing on my general HVAC knowledge (such as it is) on where a fault might be. It still sounds like there's a power line after the switch that has a short or a high resistance point on it.

[Tim C]

Don't forget the trunk gasket. It may be the exhaust getting into the trunk and the vintage air is circulating it. Just a thought.