First post, and I admit I’m new, but I DID look for this issue already. I start this thread with great hesitation.

Bought a 2013 g37x Thursday night. I love it, and would like to confirm I don’t have an issue with my heater core. 3 year unlimited mile warranty, so if it needs fixing, let’s fix it!

Issue:

Excessive condensation when I turn the vehicle on. Haven’t noticed a sweet smell, but it is musty just after starting the ac. Smell

goes away after. The defroster works on the rear window, little black lines melt ice/clear condensation. Heat does work. Only thing that makes me wonder about this is the drastic difference between 61 degrees and 62…61 is too cold, 62 is too hot. Seems odd. Anyone else have this?

 

To have that much condensation accumulate on the INSIDE of your windows- especially the rear glass- leads me to suspect you may have standing water on the floor. These cars are becoming notorious for leaking whether it be due to faulty sunroof drains, failing cowl seals or worn door/ pillar seals. A little bit of "fogging" is usually normal (depending on your climate) but that condensation (based solely on your pic) is outright extensive and NOT normal (unless you were christening the rear seat for some adult activities ).

I'm sure your heater core is fine. It is only a small heat exchanger (radiator) that circulates hot coolant from the engine. It fails by leaking coolant. You would know if you had a coolant leak.

In some very rare cases, the evaporator drain line can become clogged with dirt/debris which would allow condensation from the evaporator to backup and overflow the drain pan. If you are in a relatively humid climate, with the AC on, you should be able to see water dripping from underneath the passenger floor area of the car to the ground

You don't specify whether your car is a Coupe/sedan/'Vert, however, I would first suggest you pull up on the carpet and check for puddles (plenty of threads on here to show you how). Also, you can look into changing your cabin air filter. Not only is it a good maintenance item, but if the filter is wet/shows evidence of having been wet, this will lead to other diagnostic possibilities.

As for your temperature blending, you may have a sticking/faulty blend door actuator/motor. I won't get into that until you have had a chance to look into the above.

A lot to digest, but relatively easy to troubleshoot/resolve.

 

[QUOTE=ILM-NC G37S;4304889]To have that much condensation accumulate on the INSIDE of your windows- especially the rear glass- leads me to suspect you may have standing water on the floor. These cars are becoming notorious for leaking whether it be due to faulty sunroof drains, failing cowl seals or worn door/ pillar seals. A little bit of "fogging" is usually normal (depending on your climate) but that condensation (based solely on your pic) is outright extensive and NOT normal (unless you were christening the rear seat for some adult activities ).

I'm sure your heater core is fine. It is only a small heat exchanger (radiator) that circulate hot coolant from the engine. It fails by leaking coolant. You would know if you had a coolant leak.

In some very rare cases, the evaporator drain line can become clogged with dirt/debris which would allow condensation from the evaporator to backup and overflow the drain pan. If you are in a relatively humid climate, with the AC on, you should be able to see water dripping from underneath the passenger floor area of the car to the ground

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sorry, she’s a sedan. I love the car, and I thank you for your help. That makes so much sense. I will go look under carpets now. I’ll start in the back, but I should say I get a musty ‘wet’ odor when the AC kicks on for a minute. If you have any other ideas I am happy to listen! Thanks again!

 

It is more common for the front passenger side to leak moreso than the driver and rears, but in the event of a leak, as water accumulates it also migrates to the rear (it is how the floor of these cars is designed). Again, given the amount of water on the REAR glass indicates to me something is awry back there. A thorough check of all four corners will confirm/eliminate that suspect.

Again, check the cabin air filter. Any indication of water in/on the blower box will help narrow down potential trouble spots.

There are "supposedly" a number of foaming aerosol cleaners that folks spray into the evaporator drain tube in a effort to clean & disinfect the evaporator core. This area is already a humid hotbox and prone to all sorts of nasty contaminants. I do not know offhand how effective those treatments are as I've never used them personally.

 

Thanks again for your help. I haven’t lifted the carpets, but I don’t feel any moisture in any of them. I’ll check the air filter next, I worry I’m going to have an issue thats expensive, but I can’t recreate the issue when I turn the air or heat on full blast. Any other thoughts before I send it to the shop?

 

You probably wouldn't be getting that much on the rear glass, but check the spare tire well too for standing water. I had a car pool water there when a tail light gasket failed.

 

Good catch, Epiphany. Never thought to look in the trunk/spare tire wheel well.

You will have to pull up the carpet to make sure there is no standing water. There are recesses in the floorpan where water will accumulate. Placing your hand on top of the carpet will not suffice.