TIL where rear heater vents are located

[Wallythacker]

When I bought my 2014 the sales guys pointed out that the rear heater vents were optional and I would come to appreciate them. I never had a chance.

When I got my 2017 because it was an ES I figured there were no rear heater vents.

Yesterday while mounting my HF radio under the seat I noticed this raised lump in the way. I was shocked when I reached around it and felt HOT air flowing out!! My ES does have rear seat vents.

So, as a test I plugged the rear seat vents, both sides, and the VOLUME of air from the front vents was DOUBLED!! Or so it felt. What it felt like was the HIGH speed of my 2014 climate control Mirage.

So here's what I was wondering. Where are the rear heat vents fed from? I would think there's tubing from the main plenum that must be very close to the the fan as the volume of air from those little vents was impressive.

Has anyone here taken out their entire front carpet for whatever reason and noticed the ductwork for the rear vents? Also, since I thought they were optional on my 2014 and not available at all on an ES who else here has the vents?

[mohammad]

I believe all trims have the rear vents. they are mentioned in Doug's YouTube review of the car. I have no idea how the vents are run but you can see the Mirage with the floor exposed in this thread: https://mirageforum.com/forum/showth...-with-pictures! Foama also has advice written somewhere on the forum about how you can plug the rear vents with sponge to receive more warm air up front.

[Wallythacker]

I believe all trims have the rear vents. they are mentioned in Doug's YouTube review of the car. I have no idea how the vents are run but you can see the Mirage with the floor exposed in this thread: https://mirageforum.com/forum/showth...-with-pictures! Foama also has advice written somewhere on the forum about how you can plug the rear vents with sponge to receive more warm air up front.

I recall that thread and for the life of me I do not see any vents once the interior is removed which leads me to think the vent are plastic and come up with the carpet. But the question still remains, what feeds these vents? Is there plastic ducting all the way from the dash/fan area down to the floor? I just don't get it.

When I plugged those vents I noticed a HUGE improvement in airflow from my AC. That surprised me. My AC now feels as powerful as my 2014 AC. (the climate control in the 2014 has always struck me as much better than my 2017)

[foama]

My 2014 poverty edition has them.

[7milesout]

Wally - Generally the ducting is attached to the fan assembly in the vicinity of the glove box / center console. And generally, it runs down from that area alongside and "parallel" to the "tunnel." It is a blow molded thermoplastic duct so it is shaped and curved however an engineer wants it to be. They are generally made "flat" in the area of the tunnel, down from fan assembly, laying against the "tunnel", and then up under the center console generally, or at least on the passenger side. And then they run toward the back, still flat, up under the floor console. They're made "flat" to fit without being noticed. Very sneaky.

In the vicinity of the seat, they break out from under the console and run under the seat. Once under the seat they can sometime change shape to whatever works best in that area, or whatever molds the easiest. And then the tubing terminates in such a way as to vent air in a direction that clears the bottom of the front seat allowing air to better fill the rear seat area. All this is done under the carpet too, except where the vent terminates.

I got to be a liaison engineer for my Japanese counter-parts in Japan while developing and launching the Lexus RX-330 in Canadia back about 20 years ago.

My Lexus engineer for a month was asking me to confirm the "written form" (that is EXACTLY what he said), inside a duct. I checked with the vendor, with the plant, and with the engineer what this "written form" was. Finally when he was at my office (fly over from Japan) I asked him, "would you please write that down."

This is what he wrote down for "written form." URETHANE FOAM.

[Wallythacker]

The ductwork for the rear vents must be connected up in the dash at the point the air is diverted by the selector knob. Not all modes have air flowing to the ducts full-time. Since the air IS being diverted at the dash it would be minimal for Mits to install another switch to disable the rear vents. But asking for another $2 switch on a cheap car is expecting too much.

The ductwork under the carpet must be brilliant as I can't see where the ducting is. It's really well hidden.

I chuckled at the whole urethane foam thing. I saw it coming, but it's still funny.

[Wallythacker]

Ok, I don't know what to make of this.

My 2014 has the plugged RHS climate control system.
It also has the optional (AFAIK) for 2014 rear seat vents.

Since I gained a LOT plugging my 2017 vents I thought to try it on my 2014

Results.
When I plugged the 2014 rear vents the RHS at the dash became as powerful/Hot as the LHS. WTF????

I REALLY need to see a easily decodable picture of the underdash routing of the vents. And a clear picture of the airflow from the dash diversion to the rear vents. There's no reason I can think of the dash vents would suddenly flow normally just because the read vents were closed off.

[Fummins]

Ok, I don't know what to make of this.

My 2014 has the plugged RHS climate control system.
It also has the optional (AFAIK) for 2014 rear seat vents.

Since I gained a LOT plugging my 2017 vents I thought to try it on my 2014

Results.
When I plugged the 2014 rear vents the RHS at the dash became as powerful/Hot as the LHS. WTF????

I REALLY need to see a easily decodable picture of the underdash routing of the vents. And a clear picture of the airflow from the dash diversion to the rear vents. There's no reason I can think of the dash vents would suddenly flow normally just because the read vents were closed off.

All the cars I looked at all have the same crappy looking little vents under the front seats that stop near the front of the front seat bottom(if seat is back all the way). They run up the center of the floor and go to a tee fitting into a single hose then connect to the center of the heater box between the right and left rinky dink floor ducts. I've never fiddled with my temp controls much but remember always having frozen feet when it's -20 to -40. At least on my 20 min commute.
I'l post pics later. I found a car with no dash a few mins ago.

[Fummins]

[Wallythacker]

Thank you so much for that!

Finally the mystery of these things is solved for me!!! mostly.

I'm no airflow engineer but I suspect if smooth tubing was used the airflow would increase by a factor of 2. Also, it just looks badly engineered. Like an afterthought.

If I get ambitious this summer I'll replace the rippled tubing with smooth and see if there is an easy way to mount an open/close flapper to prevent any air from entering the downtube.

I'm still trying to figure out why the volume evened out when I plugged the exits