Burnt oil smell coming through vents.

[GT Fanatic]

2005 G35 Sedan 2wd.

My wife is pregnant and drives about 45 minutes to work. She says when the heater is on with the compressor she can smell burnt oil. But if the a/c compressor is off, she really doesn't smell anything. What causes that to happen?

Thanks in advance for any and all help.

[Coupe81]

Heater core? My f-150 was doing the same thing,ended up being the heater core.

[shumpertdavid]

Sounds like you need to drive the car and confirm the odor. The compressor being on or off shouldn't affect an "oil" smell. It would however cause odor if the a\c clutch were slipping or having problems. It will be more of an electrical\overheated brakes type odor. I don't know the best way to describe the odor but it's distinct when you smell it. Heater core could be a possibility but it will have the sweet antifreeze type odor, and if it's leaking much at all would be putting a film on the windshield while on defrost. If it's actually an oil smell, the valve covers could be leaking down onto the exhaust manifolds. The climate control may be switching between fresh air and recirculate and while in fresh air mode allowing the burning odor into the cabin area.

[JC316]

Could it be a pregnant wife trying for a new car? Like shumpter said, the a/c wont cause an oil smell. In fact, the only thing that I have seen cause that is the valve cover leaking onto the manifold and then the fresh air intake sucks the smoke in.

[AdRock]

The climate control may be switching between fresh air and recirculate and while in fresh air mode allowing the burning odor into the cabin area.

This is my first thought also. That's the first thing I'd check. Also, check the seal at the back of the hood. If it's not sealing correctly it'll let air from the engine bay get sucked right into the fresh air intake.

[TruestreetTim]

This is my first thought also. That's the first thing I'd check. Also, check the seal at the back of the hood. If it's not sealing correctly it'll let air from the engine bay get sucked right into the fresh air intake.

That was the problem in my 5.9 Jeep oil smell and all. The brain (control panel) for climate control started opening and closing the vent at random. At 73* it would blow ice cold A/C. Turn it to 74* and it would blow 100% heat.