Kristian_Solem

Car in question is a clean well maintained unmodified Boxter-S 130K. I get a strong odor of coolant through the interior vents except when in Recirculate mode. There is no significant loss of coolant or drip.

New to the forum. Cool place!

Macster

Seems a bit strange you do not smell the odor in recirc mode. AFAIK the air passes through the heater core regardless of whether it comes from outside the car or from inside the cabin and the heater core is the only source of anti-freeze odor I can think of that you would smell.

Unless, unless the leak was from some other place and you smell it as it is pulled in from air from outside the cabin while in recirc mode the cabin air is of course free of any anti-freeze odor.

Regardless there is a leak in the cooling system. Be sure you are not being fooled by a stain in the tank that makes it look like the level is ok when it is not. When the system is cold remove the cap and actually verify the level is ok.

You need to check the radiators for any sign of a coolant leak, and the hoses/tubes under the car and at the water pump and the coolant tank.

One thing you can try to bring the leak out is to drive the car until it is warmed up then at a good spot raise the rpms to 1500 and hold until you hear the radiator fans come on. The A/C should be off. Then shut off the engine and let the heat raise the temperature and pressure of the coolant. If there is a leak it will I think become obvious.

The above finally made it clear to me that my car's tank was cracked when the coolant started gushing out.

Kristian_Solem

Thanks for that. I appreciate the info. I used to be pretty good with the air cooled Porsches. I'll try your ideas.

FWIW the odor (which is strong) comes and goes almost instantly when switching in and out of recirc mode, there's no question about that connection. Also the car can be standing or moving so long as it is warmed up.

Hopefully I'll make it spring a leak tomorrow under controlled circumstances.

Macster

This strongly suggests to me my assumption the air passes through the heater core (I mistakenly typed evaporator which I have now corrected) when in recirculate mode is apparently mistaken...

Wait, this works not only during A/C operation but heat operation so the air has to pass through the heater core regardless of the setting.

Well, I'm at a loss then to explain why the odor comes and goes when switching into or out of recirc mode.

Regardless, one should not smell anti-freeze/coolant at any time and especially from the heater/AC air vents.

Just a thought: You sure you smell anti-freeze? It has a distinct odor to be sure. But these cars can stink from other things. The A/C can develop a foul odor from the cabin filter. Also, water drains can back up and water can collect in the drain basins under the front trunk cover just ahead of the windshield and mixed with the litter that collects stink.

BTW, the odor going away when you switch to recirc mode strongly points to the odor not coming from either the heat exchanger or the evaporator but from a source that is outside of the heater/AC system proper.

Kristian_Solem

Thanks again. Got sidelined today but I'll check all your leads. I am pretty sure it is coolant I smell.

If anything this car has been over maintained and I know the cabin air filter is new. FWIW it got a new motor at 100k due to IMS failure.

And you are correct about the glass staining where you visually check the coolant. The coolant is visible down there, but well below where I thought it was just going by the visual.

terbiumactivated

Coolant smell through the vents could be the heater core, check the floor for any signs of leaked coolant.

q2usmc

Sounds like the same issue I had on my '98 Boxster about a year ago. Turned out to be the heater core! I detected a "sweet" smell and a slight mist coming through the vents. Heater core was leaking so I had it replaced.

Macster

Agree: The heater core is the likely source of the odor. The report the odor goes away when the system is switched to recirculate mode kind of makes think it could be something else. Regardless, the heater core should not be that hard to eliminate.

Kristian_Solem

Just to wrap it up, it was the heater core. Symptoms were:

Odor of coolant with AC on, except when in recirc mode.

Odor of coolant with heat on in all modes.

Thanks everyone.

Macster

Glad to read you got it all sorted. I still do not understand the absence of the odor when in recirc mode but it doesn't matter now.