Toyota Sienna Forum - siennachat.com banner

1 - 7 of 7 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
I'm guessing the previous owner didn't use the rear A/C or heat much, because when I turn it on there is an acute mildew smell in the cabin that is otherwise never present.

Any tips on how to take care of this?
 

·
Registered
Joined
·
151 Posts
I'm guessing the previous owner didn't use the rear A/C or heat much, because when I turn it on there is an acute mildew smell in the cabin that is otherwise never present.

Any tips on how to take care of this?
The good news is that, if the smell only comes when you turn the rear on, you almost certainly have something in the rear A/C plumbing rather than something more expensive like a large coolant leak or a failing heater core. Unfortunately, if there's good news, there's often bad news. My guess is the "something" in the rear is almost certainly a mouse nest (or 10). The reason I say that is, old french fry, a dropped orange peel, half a muffin or even a whole cheeseburger (all things my kids have dropped on my van floor) would have dried out and desiccated to the point that nothing could grow on it anymore. Mice, however, make a nice fur and fluff clump which sucks moisture out of the air and re-hydrates all their urine.

Whether it's a mouse nest or a cheeseburger, you can try cranking the heat for an extended period of time to make the smell go away for a bit, but it will probably come back unless you remove whatever is in there. I would start with a shop vac with a crevice tool. If that doesn't work, you can either remove the channeling to clean it or try to make a custom attachment for your vacuum that uses a small hose on a funnel so you can get it further in there. They make sprays that work, for a time, but often they are just cover sprays and even the good ones that do sanitize the system obviously don't remove the source, so the smell comes back.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #4
I think it was just not used very often by PO. I bought the van last year and I'm only the second owner. The original owner was in L.A. area, so probably didn't use the rear heat very often.

I've been running it full blast with heat to max and the smell is nearly completely gone now.
 

·
Super Moderator
Joined
·
5,022 Posts
Toyota sells a 'kit' for removing mildew from the evaporator & heater core regions. No idea how well it works, but something to consider.

 
  • Like
Reactions: HappyInASienna

·
Registered
Joined
·
11 Posts
Discussion Starter #6
Was AC in the rear an option? It seems like it is only a heater, because when I turn the AC on, the AC light only turns on if the front fan is on and the air coming from the rear feels not cooled, although I haven't been a passenger in the rear and really investigated (I know AC isn't always effective when idling).
 

·
Super Moderator
Joined
·
5,022 Posts
The rear system is both AC & heat.
 
1 - 7 of 7 Posts
Top