Suburban Exhaust Fan

[Lykos]

Hey there.

I've been a Jeep XJ guy for a long time but just became the owner of a 1996 Suburban.

Here's the question. When sleeping in the XJ I would hang a Wal-Mart battery operated fan in the window to keep interior temps down.


As I look at this Burban I see it has ceiling mounted HVAC vents.

So I'm thinking I could possibly mount a thermostat controled exhaust fan and plumb it into the factory vents. Thereby using the factory ducts to move air from inside out rather than outside in. All of which would be independent of the factory HVAC. There are some details to work out such as where to mount, type of fan, how to switch from exhaust to regular HVAC...

I know it can be done but the question is should I do it? I'm going to be able to choose the Windows when I sleep one way or another even if it means cutting the roof to install a vent fan. Which is the option I'd like to avoid.


Thoughts? Other than "geeze what a stupid
question." LoL

 

[DaveNay]

Might be easier to just modify the existing fan circuit so that it can be switched on with the key off.

 

[Lykos]

It would be but I want it to pull hot air out.


I've run exhaust fans in tractor trailer sleepers and they do wonders for bringing down interior temps.

 

[DaveNay]

It would be but I want it to pull hot air out.


I've run exhaust fans in tractor trailer sleepers and they do wonders for bringing down interior temps.

Can a squirrel cage blower be run in reverse?

 

[snowblind]

So I'm thinking I could possibly mount a thermostat controled exhaust fan and plumb it into the factory vents. Thereby using the factory ducts to move air from inside out rather than outside in. All of which would be independent of the factory HVAC. There are some details to work out such as where to mount, type of fan, how to switch from exhaust to regular HVAC...

I know it can be done but the question is should I do it? I'm going to be able to choose the Windows when I sleep one way or another even if it means cutting the roof to install a vent fan. Which is the option I'd like to avoid.

Thoughts? Other than "geeze what a stupid
question." LoL

Your HVAC ideas are maybe not so good. I would pursue a different method.

Window mounted fans/vents are probably better. This guy did a cool one in a van window http://www.expeditionportal.com/for...ana-AWD-De-Conversion-(Dodge-Ram-replacement)


Matt

 

[PolarrrBearrr]

I own a '96 that was once a fleet vehicle without AC. I am currently adding in both rear and front AC, as well as updating the interior. I had to put in a new headliner for the roof AC vents. The vents are just held in place in the headliner with metal clips - the "ducting" is actually built into the headliner. The headliner is molded with valleys, and then it has other pieces of cardboard glued over those valleys to create the ducting. There is no plastic in there. If you were to put a rooftop fan and vent in, it would require you to cut the headliner, and connect it into the housing on the fan. If it should ever leak, you have destroyed your headliner - and more than likely, you'll trap moisture in there, and possibly rot the roof. The only actual piece of plastic ducting is by the seatbelt on the passenger's side in the C-pillar.

It might be easier to rewire the rear AC unit with a separate switch to bypass the key, or rewire the controls over the second row of seats. This way, you can control everything laying in the back of the truck. I've slept in the truck during the winter, and with the center row of seats folded forward, it was a stretch to get to the keys to hit accessory and turn on the heat.

Your other option, would be to get a inverter and battery and mount it in the rear of the truck (GOD knows there is enough space in there!) and get a small plug in fan and set it up wherever... maybe replace the base with a suction cup so you can stick on the inside of one of the windows? This way you can open the window on one side, put up a screen and it can suck air in?

I'm just spit balling here.

 

[Lykos]

Your HVAC ideas are maybe not so good. I would pursue a different method.

Window mounted fans/vents are probably better. This guy did a cool one in a van window http://www.expeditionportal.com/for...ana-AWD-De-Conversion-(Dodge-Ram-replacement)


Matt

I believe you're correct.

 

[Lykos]

I own a '96 that was once a fleet vehicle without AC. I am currently adding in both rear and front AC, as well as updating the interior. I had to put in a new headliner for the roof AC vents. The vents are just held in place in the headliner with metal clips - the "ducting" is actually built into the headliner. The headliner is molded with valleys, and then it has other pieces of cardboard glued over those valleys to create the ducting. There is no plastic in there. If you were to put a rooftop fan and vent in, it would require you to cut the headliner, and connect it into the housing on the fan. If it should ever leak, you have destroyed your headliner - and more than likely, you'll trap moisture in there, and possibly rot the roof. The only actual piece of plastic ducting is by the seatbelt on the passenger's side in the C-pillar.

It might be easier to rewire the rear AC unit with a separate switch to bypass the key, or rewire the controls over the second row of seats. This way, you can control everything laying in the back of the truck. I've slept in the truck during the winter, and with the center row of seats folded forward, it was a stretch to get to the keys to hit accessory and turn on the heat.

Your other option, would be to get a inverter and battery and mount it in the rear of the truck (GOD knows there is enough space in there!) and get a small plug in fan and set it up wherever... maybe replace the base with a suction cup so you can stick on the inside of one of the windows? This way you can open the window on one side, put up a screen and it can suck air in?

I'm just spit balling here.

Thanks!

This is good information. I'd of hacked up my headliner not knowing any better.

 

[rayra]

Can a squirrel cage blower be run in reverse?

The motor can be, but the fan blades aren't shaped correctly.


And aux battery circuit with a switch in the rear by the rear ac fan to control it separate from the vehicle systems would be interesting, btu have to wonde rwhat the backfeed trouble might be. Maybe a type of lockout switch that disconnects the factory circuit and engages the new circuit.


I just happen to have pulled apart the rear of my '02 Sub today and have a nice rear AC pic. Don't expect the earlier model to be substantially different. There's room to do a lot of things behind the trim panel, but quite the complicated project and you still wouldn't have a duct dumping to the outside, unless you make a flex pipe or somethign that quickly attackes to the ceilign vents to direct the air out.

But frankly the easiest way to achieve what the OP wants is just make a simple variation of this -

make a window insert out of 1/4" pressboard that you can lodge in the doorframe at the top of the window opening. use the window to hold it up into the top of the opening. Attach a row of small fans or go as large as the fan in the picture. place it on the inner side of the frame and cover the outer face with screen mesh. Use 12VDC computer cooling fans, cheap and quiet. Wire it up with a 12v cig lighter plug and jack it right in when you want it. Put a switch on the insert piece so you can readily control it. Add a rheostat / speed control, even.
Really easy and fast to build and you don't have to hack up any of the factory hardware or ducting.
And just put it in the window on the other side when you want to pull air IN with it.

 

[PolarrrBearrr]

The only difference between our rear AC unit and the one posted above is that the fan actually sits vertically (if you want to consider the one in the image horizontal). For the most part, they are basically the same thing, including the ducting running up to the headliner. The fan unit is the same as the one under the dash - the fan is like a barrel, so you would be unable to move air with it in reverse.

It actually just occurred to me - you wouldn't be able to add a switch in the back to run the AC off just the back unit either. The lines for the coolant are tapped into the one for the front unit. Much like a normal vehicle with one AC setup, you need the engine on to run the compressor. At best, you might be able to just run the fan alone, but it will only be moving the air in the truck.

An external fan like the one in the police cruiser above is probably the best bet. I'd also venture a guess that since these trucks were used as PD, MICU and various other emergency vehicles, something like what is shown on the cruiser probably already exists somewhere.

 

[chilliwak]

There is a member here on the site called Northman that knows where to get aftermarket vents that you put in the partially open window of your `Burb´. You get a couple of these vents and then make a home made set-up with computer fans kind of like the system the previous poster mentioned. I hope this helps. Cheers, Chilli...

 

[Lykos]

Thanks for the responses.


I'm still partial to a ceiling fan going through the roof. I found one that is 6.5 in diameter and pulls only 1.5 amps while moving 100 cfm.

I imagine it would be a fools folly to ask if anyone knows exactly where in the rear headliner the ductwork is but I'll ask anyway.


Does anyone know exactly where the rear ac ductwork runs through the headliner?




I'm thinking stealth here. If I am forced to crash in a parking lot a window fan screams there's someone inside. The roof vent is a lot less noticeable.




I have a couple window fans I used in my Peterbilt years ago. They are awesome at circulating air and bringing down inside temps.

 

[rayra]

The backseat vent duct runs across the ceiling over the headrests of the 2nd row seats, from the larger passenger-side 'C' pillar. Most folks never notice the right side 'C' pillar is much wider than the driver's side. In the later series trucks with the form-fitted headliner you can plainly see the hump where the duct is. .

Problem with most of the 'camper' style roof vents is they are quite obtrusive, usually have a large cover that tips up.

The window fan grill can be quite discrete. Make an insert piece as I described earlier. Wrap it in black screen fabric. Mount the fans to the inside, using all-black fans. Paint out or remove the labels from the back side of the fan hubs (that direction faces the way the air is being blown). In a parking lot at night, with tinted windows, it won't be noticeable unless someone looks right at it.
I'll partially make one tomorrow, won't take much more than an hour. Don't have any unused fans laying about, but I can simulate those.

Does the vehicle have a sunroof? I'd consider adding one if it doesn't and then fabricating a clip-in fan mount that pushes air out of it when you want. Just snap it into the sunroof opening when you are making ready to camp.

 

[Lykos]

Thanks for the description!

This is the fan I'm looking at.

http://www.etrailer.com/Enclosed-Trailer-Parts/Ventline/VP-543SP.html

I wish mine had a sunroof. But I've grown fond if my overhead console.


I had a window fan set up in my Cherokee. But, the rear Windows in the XJ were much smaller and square. As you know the 96 Burb Windows have an arc that makes it a bit if a different story. I can still make one. But I can't let go of the ceiling fan idea. I know I'm being picky but you probably know how it is when something gets stuck in your head.



So, based on what you just described I could cut the middle of the roof a foot or two front the rear hatch and miss the vents?

 

[Lykos]

And, please pat a photo of your window fan set up when you get it done. I'd love to see it. Might change my mind...