Smell from ac



My wife complains of a very bad smell when the ac is on (not the vent). It still blows cool air but with a bad odor. I checked the coolant level and have NOT seen it go down. The repair man said it was likely the grease from the axle?? but we had that replaced and the smell has persisted!

From other helpful links it looks like: a) the heater core? (why am I not seeing coolant loss?) OR b) freon or a/c lubricant (still cold?)

What is your vote?

Very frustrated b/c I might not have had transmission AND axle work done on this 99 Expedition if I had known there was something else!


It is a sweet smell? a moldy smell? a burnt smell? How about a hint?

BTW what axel got the grease?


Its a syrupy smell. It comes on immediately with the heat and takes some time to build up with the a/c. I still ahven’t noticed any coolant loss but suspect is the heater core that needs to be repaired- great.


How much does a heater core cost for a 99 Expedition?


The syrupy smell pinpoints the problem to the cooling system. It doesn’t have to be the heater core. A minute leak from something under the hood can still waft vapors into the cabin.

I am surprised a mechanic would mention axle grease. Maybe he knows something you haven’t told us. In any case, get a second opinion from someone else.

If you have to replace the heater core, understand now the part itself is but a small part of the final bill. It’s the labor costs that will eat you up.


Why does the onset of the smell happen quicker when I turn the heater on (vs the a/c)? Can that tell me anything that might help me with the mechanic?


It hardly matters because the mechanic will want to disassemble your dash in any case. He is probably on the right track. You will likely wind up with a new heater core.


To wrap it up- it was related to the condenser system behind the dash. There was a small coolant leak which created the fish smell and it in turn caused a freon leak which was the syrupy smell. The mechanic was very apologetic and reduced the labor charge on this job by a significant amount.
Thanks for all the car talk input!


My 96 accord does the same thing. Only difference is that its more with just the vent on , almost goes away with the AC on. Havent tried the heater though. Its there when I turn the engine on, then goes away in a minute or two. If I keep the vent straight on my face sometimes I can smell it but not as strong as the initial one. I’ve tried febreeze under the hood near the vent opening, didnt make much difference. Any suggestions.