Splice Into Fan of Rooftop AC
- Thread starter Schwimms
- Start date
You are going to need a HUGE battery bank to run any roof top A/C System! (I assume you are talking about an add on RV A/C unit? Factory rear roof A/C requires the engine regardless to run the compressor.)
Roof RV roof units are terribly inefficient, and draw huge currents..12-15 amps (or more) running, ten times that to start (or more). 15 amps of 120 vac Is 150 amps at 12 vdc. Consider how big a battery you need to run 150 amps for very long. Some ”modern” A/C units Use less but I don’t know of anyone who generally is able to run A/C off a battery very long.
Icarus
Roof RV roof units are terribly inefficient, and draw huge currents..12-15 amps (or more) running, ten times that to start (or more). 15 amps of 120 vac Is 150 amps at 12 vdc. Consider how big a battery you need to run 150 amps for very long. Some ”modern” A/C units Use less but I don’t know of anyone who generally is able to run A/C off a battery very long.
Icarus
Cheyenne
UK 2004 T1N 313CDi
Start
So the load on a battery would not be the issue, the tapping into the MB wiring would be the issue.
Keith.
I started answering along the same lines then realised Schwimms actually asked "I'd like to be able to run the fan of the (rooftop) AC unit... off of a battery bank."
So the load on a battery would not be the issue, the tapping into the MB wiring would be the issue.
Keith.
autostaretx
Erratic Member
I'd offer up my usual batch of 2007 documentation, but a quick look at the 3rd party diagrams didn't show the rooftop fan as an isolated item (figure 5) ... and the 2007 diagrams are really obsolete by 2017.
--dick
oh heck... maybe it's in the official diagrams: (or at least a "kind of like...")
http://www.diysprinter.co.uk/reference/2007-sprinter-service-information.pdf <-2007 MB service manual
http://www.diysprinter.co.uk/reference/2007-sprinter-wiring-information.pdf <- MB wiring diagram from above
http://www.diysprinter.co.uk/reference/2007_Wiring-sprinter-2500.pdf <-- 3rd party wiring diagrams
--dick
oh heck... maybe it's in the official diagrams: (or at least a "kind of like...")
http://www.diysprinter.co.uk/reference/2007-sprinter-service-information.pdf <-2007 MB service manual
http://www.diysprinter.co.uk/reference/2007-sprinter-wiring-information.pdf <- MB wiring diagram from above
http://www.diysprinter.co.uk/reference/2007_Wiring-sprinter-2500.pdf <-- 3rd party wiring diagrams
AC units do not bring in fresh air...they recirculate and cool the interior air. Running an AC unit in just fan mode would be kinda pointless for ventilation.
...and of course you can not run a factory rooftop AC off batteries or generator since it runs off a mechanical belt driven compressor from the engine vs a typical 120v electrical motor driven compressor of a RV AC unit.
...and of course you can not run a factory rooftop AC off batteries or generator since it runs off a mechanical belt driven compressor from the engine vs a typical 120v electrical motor driven compressor of a RV AC unit.
I recently purchased a 2012 144 Sprinter with the rooftop AC unit for conversion to a camper van and had the same thoughts being discussed here. My wife and I are struggling with the question of "Should we remove the rooftop AC Unit or not?" We live in Texas, so AC in the summer would be nice, but already have 2 100watt solar panels mounted on the roof behind the AC and really no room to add a rooftop 12V Fan, or any more solar. So, the question at hand is.
What is more valuable, a rooftop AC unit that can only run with the vehicle on, or a rooftop vent fan that can be run at any time?
What is more valuable, a rooftop AC unit that can only run with the vehicle on, or a rooftop vent fan that can be run at any time?
We have a Roadtrek on a Sprinter chassis. It came with both the rooftop AC and a Fantastic Vent roof fan.
IF you can avoid traveling in really hot climates.... We use the vent fan almost exclusively by having it on "exhaust" setting and cracking rear side windows. Very effective. There have been a few times we've been caught in unusually hot weather, however. In those cases, hit a campground, plug in, and live with the extremely noisy (but effective) rooftop AC. Otherwise the roof fan works very well.
IF you can avoid traveling in really hot climates.... We use the vent fan almost exclusively by having it on "exhaust" setting and cracking rear side windows. Very effective. There have been a few times we've been caught in unusually hot weather, however. In those cases, hit a campground, plug in, and live with the extremely noisy (but effective) rooftop AC. Otherwise the roof fan works very well.
Sadly we do not have the option of picking a campsite to run the AC (it is the factory installed MB unit that requires the engine to run the compressor) that is our main dilemma, will the roof top vent fan keep up with the warmer climate we live in, or is keeping the AC a necessity? I would be curious to see if anyone has done any tests around running the AC in a well insulated van and how long the van remains comfortable after shutting it off, as well as how many degrees the fantastic fan can cool off the van?
Timemachine
New member
I'm in a similar situation with a recently purchased 2016 with rooftop A/C that I doubt I'll use but hesitant to remove yet.
How did you mount your solar panels? I assume yours doesn't have the factory roof rack mounts?
Thanks in advance,
Greg.
Currently mine are just mounted using Renogy Solar Panel Mounting Brackets straight into the roof and sealed with self leveling dicor rv roof sealant. While it does work, and has never leaked on us, I wish we had room for a 3rd panel and a fantastic vent fan, I am currently looking into affordable roof rack options that can help us accomplish this.
Attachments
I did find these, that seem promising and affordable.
Edit: If you go to the LAST photo of the second link, it shows a 144 passenger with solar mounted!
Sprinter Roof Tracks - VANTECH USA
This Sprinter Track Kit fits the 2007-On Dodge & Mercedes Sprinters with. Track include all necessary hardware. The Sprinter Tracks allow you to install a Rack Systems, Lights or other equipment onto the roof of your vehicle via. sliders. Tracks are only available in silver.
vantech.us
Sprinter Solar Panel Roof Bar - High Roof
07+ Sprinter solar panel roof cross bar Designed for mounting solar panels No additional holes in your roof Mount solar panels between 2 solar roof bars 47.25" Usable length, 1.25" square tube Specifically designed for awning clearance This model made for High Roof vans Attaches to OEM roof...
rbcomponents.com
Edit #2 BEWARE: Second link is only for ONE cross bar ?
Timemachine
New member
So did you just screw into the roof sheet metal with shortish screws without removing the headliner?
Yes, here is an affiliate link to the mounts that I used, it came with screws that are quite long, but they did not interfere with my headliner since there is a large airgap above it. I went out to the van to snap this photo since we just removed the headliner to insulate. You can see they do not go lower the support beam in the photo.
Attachments
Timemachine
New member
Great, thanks for that.
(affiliate links below)
Super excited after taking some measurements while getting those photos. The usable space on top of my van behind the Factory AC unit is 54.5" wide, and 52" length. With that space I should be able to turn my current solar panels which are (19.2x44.2)to run the lengthwise with the van, and install a fantastic fan (17.5x17.5 but only 14.5x14.5 hole, so the edges on the roof will be under the edges of the solar panels) in the middle!
I will report back once the fan comes in the mail in a few days to verify the fit worked!
Timemachine
New member
It would be great if you could post your progress on this thread. It's still winter here but I'd like to make some decisions soon on what direction to go.