Dealership cannot Diagnose Origin of Problem!

2012 Toyota Yaris 4-door sedan, basic no-frills car, bought used 6 months ago.
Was a fleet vehicle (probably a rental), came from a southern state.
I purchased an extended warranty for the car.

"Dirty Sock" smell began coming out of all vents 2 months ago when I use heat.
Is especially worse when it rains.

Dealership used a powerful, foam chemical evaporator cleaning kit but as soon as chemical dissipated, the dirty sock odor was still there, pungent as ever.

Next, I spent $1400 having them tear apart dash and replace the evaporator core itself.

Still didn't work. Odor is still there.

Called dealership back and they said it is something invisible that is impossible
to diagnose.

As a side note, I received an automated call from the dealership's Parts Dept saying my evaporator core had arrived - this is AFTER I got the car back "fixed" smelling like chemicals again...they had also added fragrances against my request...When the car was in their shop they did tell me it would be delayed by a day because the "wrong part had come in"...I sure hope they actually changed the darned thing!

There's also been a lot of other BS from them which I won't go into.

There has to be bacteria growing SOMEWHERE in this car.

They say all hoses have been drained.
Leaks?
Should I pay someone else to diagnose it?

Does your Yaris have a sunroof?

Drains have been known to come off or plug and cause water to run in to the car. It may get the headliner wet as well as the carpet. The interior intake for the HVAC system pulls air from the passenger floor area, so mildew in the carpet there could come through the vents.

Is the smell any better when using fresh air versus recirculate?

-Rod

Thanks Rod.

No sunroof.

This is definitely coming straight from the heating system itself.
Given the strange automated phone call I got, I'm beginning to believe the part didn't come in in time and they just chemicalled-up the old existing heater core. Why else would they have doused the system with chemicals again? I'm going to have to ask for proof they received it while my car was actually there.

Either that or the heater core wasn't the problem and there's a leak under the hood. I did see some rust. I'll have to put newspaper all under the hood next time it rains.

It could also be a leak from the windshield or elsewhere.

The car actually did not come with floor mats so there could be mold under the carpet. I mentioned this but they did not check it. However This happens on fresh air intake also so I doubt it's that.

I would request technical assistance thru the Toyota zone office. Info is in your owners manual. No warrantee here?

I bought a very good extended warranty.
I was told none of the work they did was covered.
I have read these things are covered and I believe whatever is causing it is covered.

I would request technicall assistance thru the Toyota zone office. Info is in your owners manual. No warrantee here?

In was also told by someone on another forum that the evaporator core has nothing to do with the heat which is all I've been using , that it is only for the A/C?

I thought it could be the heat pump but the dealership says my car doesn't have one?

You were told correctly. The evaporator core is only for the A/C, but the heater core is for the heater and resides in very close proximity to the evaporator core.

-Rod

Thank you.
I have to wonder why a dealership would change an evaporator core @ $1400 when I told them the smell was coming from my heat.

A musty smell from the HVAC vents is most often associated with the A/C system. Also, in the winter, the A/C is active when using the Defrost setting to dry out the air, assuming the ambient temp is near freezing or above. The dealer may have suspected that the smell was due to mold growth within the evaporator core fins. Air can pass through the evaporator core, even if you are only using the heat setting which would carry the smell of mold/mildew.

I'm not trying to say this was likely what was happening, just offering information as to why they may have taken this approach.

Unfortunately, considering the cost and labor to replace the evap core, I'm surprised they didn't also replace the heater core in the search for the smell since that would have only added another $100 or so to the total cost since the labor would have been the same or minimally different.

-Rod

Unbelievable.
Thanks, Rod.

In Nys, that 1400 spent for "ineffective" repairs would open the door for either dmv complaint or charge dispute!

1) i believe the evaporator core does have something to do with heating system.
I am also however hearing about people looking under heater box and unclogging drains there.

2) I got really sick over the past few days.
I don't know if it's a coincidence. It feels like the flu. I stayed out of car yesterday and feel better...ill see if being in it today makes me sick again.

ALSO: Found out yesterday that this was ALL COVERED UNDER WARRANTY...they told me it was not.

I am so upset with the pathological lies of this dealership - and don't trust them to fix anything further on my car.
I am also tired of playing mechanic with these untrustworthy places.

I'm going to have to go back in and deal with it all.

Is the heater "core" the same thing as the heater "box"?

The heater core is located within the heater box, but they are not the same. The heater core is a subset of the box, or a component of the box.

-Rod

Thanks.

I would consider the "heater box" to also contain the evaporator core and the mount for the blower motor. It's more of a generic term for the large chunk of plastic inside the cabin, under the instrument cluster, that contains the large interior HVAC components.

But, keep in mind that my experiences are general, I have no specific experience with the Yaris to know if Toyota did something atypical with that HVAC system.

-Rod

Thanks again.
I actually saw the heater box when they had the car torn apart. The evaporator core in my car sits on top of it. They say they "cleaned" the box itself but I believe they might have used chemicals in the other components inside that box (heater core etc) perhaps to save time and not have to order other parts. Hence the strong chemiCal odor. And/or Perhaps other
hVAC components are still moldy. I also don't think they really were thorough with drain pan and hoses. I understand one cannot drain hoses in this weather even in a heated garage.

Hello, I think you can buy one diagnostic tool to do your cars by yourself. Your car is 2012 Toyota Yaris 4-door. I suggest you to use the Toyota IT2.

Exactly how do you think an OBD2 diagnostic tool is going to help diagnose this problem?

-Rod