Share:
Notifications
Clear all

Exhausting Cabin Air

Page 1 / 2
NottaMiata
(@nottamiata)
Honorable Member

I am still mired in my winter-related project (I'm "pacing myself"), but I am looking way ahead to the time when it is 108F in the shade and I have a new, black canvas top. The Frog is going to be an OVEN.

So I am pondering the idea of placing a small solar panel on my dash that will run a low-voltage fan that blows air out of the car. Even a small flow will help immensely.

I am looking for a way to simply piggyback on the existing climate control ducting, hopefully, to blow hot air out. Fresh air will be free to infiltrate through any cracks, the soft top gaps, etc. However, this may change a bit if it looks like pulling unfiltered air is not such a spiffy idea.

My only concern with pulling/pushing past the filter is overcoming the flow resistance from the cabin air filter if I piggyback on the hvac. Piggybacking is not required, though. If there is another convenient, concealed exit point, I'd like to hear your ideas. Otherwise, this is a cheap, easy mod that adds tons of quality-of-life points for 2/3 of the year.

I am not after a flow rate that would keep the thing at a stupidly-ambitious level like <= (ambient + 2F), but if I could get it down to simple first-degree burns from the seat covers ten minutes after I put the top down, then that would be a success. It would be better.

Seriously, once the entire thermal mass of the car interior is at 130F, which takes about five minutes even in a white car around here, much less a black in black greenhouse like I will have eventually, it takes an hour to cool it off enough for human habitation, regardless of top-open. The surfaces cool fast enough, but its still uncomfortable when everything just below every surface is still 125 degrees.

Any ideas? Has someone already beaten me to this?

🐸, 2003, Electric Green Mica, (still !) not enough mods...

Quote
Topic starter Posted : December 10, 2019 2:03 pm
Uncle Mush
(@uncle-mush)
Member Moderator

I love the idea and don't know of anyone who has done this.  Elio was proposing such an idea for their vehicles, if I remember correctly, but doubt if we will ever see anything from them. 

ReplyQuote
Posted : December 10, 2019 3:29 pm
dev
 dev
(@dev)
Just a member. Moderator

 If I were to entertain such an idea I would have it where it can be removed easily from the cars interior and where it will have absolutely no connection the cars electrical and HVAC system.  

 Considering how much air you would need to flow to ventilate I would imagine you would need to duct it into the factory HVAC system which adds further complexity and reduced performance when you need things to operate as they should.  The only option is to duct it out the window but what do you do when it rains and worst of all everyone seeing your science project.   I doubt any cracks in the top, doors and so forth will be effective.   

 They did something like this on the Prius  premium model where the roof was solar panels but in that system it operated the AC compressor which is far better because it will actually reduce temps but from what I read, even that system wasn't all that great.   

 

 

 

ReplyQuote
Posted : December 10, 2019 3:44 pm
Uncle Mush
(@uncle-mush)
Member Moderator

What about a solar powered fan that could be inserted between the side windows and soft top frame . . . And inserted to use only when you want to use it.   Insert when you park the car and remove when you return.   It would be mostly pressure-fitted.  I seem to recall reading an article some time ago (maybe it was Elio?) that reported it didn't take much air movement to keep the parked car cooler in hot climates such as your's -- just some movement and venting.   Windows down a couple of inches with constant air flow might accomplish that.   It wouldn't be "cool" per se, but perhaps only a little warmer than outside ambient temps.  I don't know.   Just a thought. 

I just went online and Googled solar powered fan auto and see there are several products available.   Whether or not they actually work remains to be seen.  Check YouTube for some reviews,  if interested. 

ReplyQuote
Posted : December 10, 2019 5:26 pm
dev
 dev
(@dev)
Just a member. Moderator

What I have read that the large sunshade that blocks the front window is supposed to be very effective. Window tint film also but it has its own drawbacks of making a car look cheap.  

ReplyQuote
Posted : December 10, 2019 6:03 pm
pwnzor
(@pwnzor)
Reputable Member

@dev

I have a two piece reflective sun shade that I put up in the windshield RELIGIOUSLY every time I stop the car.  

It is extremely effective in that it points a large portion of the incoming radiation right back out of the car.  My side and rear windows are tinted super dark.

We get a lot of direct sunlight in the Atlanta area and my car still gets pretty warm, but my steering wheel is never burning hot and I don't even have to use seat covers.

I'm intrigued by the idea of your solar fan, though.

http://zero3nine.com/files/dospwn.gif

ReplyQuote
Posted : December 10, 2019 7:23 pm
marsrock7
(@marsrock7)
Reputable Member

Wait.... We have a cabin air filter?!?!?

ReplyQuote
Posted : December 10, 2019 8:54 pm
NottaMiata
(@nottamiata)
Honorable Member

@marsrock7

LOL. My C'rolla does. I just figured...

🐸, 2003, Electric Green Mica, (still !) not enough mods...

ReplyQuote
Topic starter Posted : December 10, 2019 9:13 pm
marsrock7
(@marsrock7)
Reputable Member

@NottaMiata

Just being facetious. 

I am genuinely interested in what you come up with for some minor "active ventilation" thou... Both my cars have black leather interior... I prefer the look and feel, but not the heat...

 

ReplyQuote
Posted : December 10, 2019 9:42 pm
Uncle Mush
(@uncle-mush)
Member Moderator

I just watched a TV news clip where they tested "Auto Cool" ( I think that was the name of the product) and compared interior temp after 2 and 4 hours in vehicles.   In both tests,  there was only a one degree difference between the control vehicle and the experimental vehicle.  So that product worked,  just not very well.   

ReplyQuote
Posted : December 10, 2019 9:53 pm
NottaMiata
(@nottamiata)
Honorable Member

Anyway, to Dev's point, I did not envision any connection to the car's electrical system, just a >5v DC panel, a <5v DC fan, and a way to allow it to exchange about as much air as it can, however it can, with all of it fully unobtrusive and elegantly re-using existing architecture, ductwork, and what-all whenever possible.

I could envision installing a check valve of sorts to be able to borrow the ducting, with it shutting to let the hvac system still function under the car's power when driving, but nothing as complex as this over-thunk Prius hijacking (as opposed to the more gentle "piggybacking" I see) of the hvac compressor and the requisite 250 watts of power to drive it. Whether the design of the hvac's airflow would even allow that theoretical one-way valve, I know not. I know precisely nothing about my ductwork or hvac system layout. No time to research that now, I'm still sanding %$#@ wheels every morning!

But, a respectable computer fan could move enough air to make a noticeable difference, I think. I would have to calculate the CFM ratings, but the cabin is what?... 50 cu ft.? Or is it closer to 17?

I am not expecting B'Jeezus to pop out of a cake here. But I also don't want a science project (nice one, Dev) in the window. Another reason I went for modding the hvac -- it's unobtrusive and already serves the exact purpose of bringing in fresh air in regular duty... but only if the magic lever is to the right! The Achilles heel of this part of the plan, ha ha -- get it all rigged up and forget to set it to pull fresh air.

But I would still piggyback on the ductwork if I could do it somewhat easily and without much risk to The Precious. I'd just have to own the dumbassery whenever I left the input source set on recirculate. But that sux though, because I very often have to set it to exclude_foul_world whenever I am following those STANK-ASS Chevys and Fords. Why do they all smell like that???

🐸, 2003, Electric Green Mica, (still !) not enough mods...

ReplyQuote
Topic starter Posted : December 10, 2019 9:59 pm
NottaMiata
(@nottamiata)
Honorable Member

@marsrock7

Yeah, it is quite possible that the greenhouse effect will overpower anything smaller than an "overthunk" 250 watt** system that pretty much has to use the air conditioner. I haven't looked at that side of the equation.

But we have all seen that simply cracking the windows and letting passive airflow happen actually makes a difference. So even a constant forced flow, even if somewhat paltry, should be better, right?

 

**- I am totally pulling that wattage figure outta the air, or outta somewhere.

🐸, 2003, Electric Green Mica, (still !) not enough mods...

ReplyQuote
Topic starter Posted : December 10, 2019 10:12 pm
haloruler64
(@haloruler64)
Prominent Member

You can get clear window tint that has the same UV protection as dark tint Dev. Great idea for keeping a vehicle cool. My untinted Lexus keeps so much cooler than my other cars in direct sun, of course it has factory UV glass. 

Problem with solar panels is that the output is super low. So I don't believe you'll get much flow going with a basic, cheap panel.

2000 Toyota MR2 Spyder, 2020 Mazda 3 Hatchback 6MT

ReplyQuote
Posted : December 10, 2019 11:40 pm
dev
 dev
(@dev)
Just a member. Moderator
Posted by: @haloruler64

You can get clear window tint that has the same UV protection as dark tint Dev. Great idea for keeping a vehicle cool. My untinted Lexus keeps so much cooler than my other cars in direct sun, of course it has factory UV glass. 

Problem with solar panels is that the output is super low. So I don't believe you'll get much flow going with a basic, cheap panel.

 I don’t have a problem with real tinted windows as long as they are not too dark.  The problem I have is with any film over glass that ruins the optical quality and makes it look cheap and plasticity from the outside. Most glass cuts down on UV radiation and some are better but on the whole I feel that the little bit of factory tint on most cars looks far more elegant and less cheap.  Most concourse, vintage and high end autos I have seen do not use film tint. 

ReplyQuote
Posted : December 10, 2019 11:52 pm
Petrus
(@petrus)
Reputable Member

I live in the south of Andalucía; 300 southern sunny days/year.

As it is a soft top, there is not much sense in being anal about security. I thus often just leave the top down or the windows several cms open and don´t lock the doors. When parking I do try to angle the car such that it gets least direct sun onto the black surfaces.

I am not that fragile but to avoid a scorched bum, the gfs have a light coloured flanel or such on the seat.

ReplyQuote
Posted : December 11, 2019 4:46 am
Page 1 / 2
Share: