On the road a Sprinter Van does an ok job to keep the interior cool with the factory AC in the front cabin. It won’t freeze the whole van but in my experience a well tuned front AC is good enough to make a roadtrip in hot climates enjoyable. Expert Tip: have a small box fan blowing cool air from the front to the back – your passengers in the back will be much happier.
Without the engine running, however you’ll have to find different solutions to keep your cool. This post describes one of those solutions: an AC unit in the back of the Van that runs on AC that you can use while camping with access to shore power.
AC Unit
There are a ton of options available. Even AC units that also run on 12V DC which would allow you to cool the back of your van while you’re driving or if you don’t have access to shore power while stationary. I’ve looked into that as well but they require more work to install due to the more complex system and they are more expensive. I’ve wanted to have a unit on the roof of the van but people also installed window units. They are much cheaper but the final result looked crappy in my opinion.
AC units come in different sizes and “cooling power” (measured in BTU). The opinion on the boards is that you should at least pick a unit with 13,000 BTU for a van of the size of a Sprinter. Another thing you should consider is the height of the unit. Since it will be installed on your roof you’ll want the lowest unit available to minimize the air drag that will ultimately impact your gas mileage while driving.
My final choice was a Coleman Mach 8 unit with 13,500 BTU, which is one of the lightest and smallest units available: it just weighs 90 lbs and is just 8.25 inches high. You can see the final result in the picture above.
Picking the location of the AC unit on the roof
Installation of the AC requires to cut a hole in your Van, so spend some time to think about where you want the unit on the roof. Criteria for the installation spot are where you want the cold air in your van and what else you plan (or already have) on your roof. Since the AC was the first thing I put on the roof of my Sprinter I could play around with multiple layouts but the final decision was to put the opening for the roof pretty close to the middle of the rear section. The main reason for this was that with this layout the AC vents on the inside of the Van would distribute cold air evenly in the rear cabin. The final position was then chosen by the measurements of the solar panels that would go behind the AC once it was installed without any rooftop space “wasted”.
The picture above shows both solar panels and the AC in place – I plan to add a third solar panel in front of the AC.
Cutting the opening in the roof
The usual warning: Measure twice, cut once. You’ll need a 14″ x 14″ opening in the roof to install the AC unit. I measured from the inside of the van as it was easier to figure out the exact position in relation to the structural beams in the roof.
The procedure for cutting is the same as with the windows: use painters tape to protect the rest of the sheet metal, drill holes and start cutting with your Jigsaw and a good blade for sheet metal.
Installing the rooftop AC unit
The installation of the Coleman Mach 8 is pretty easy. The whole unit is actually just two parts: The heavy AC unit which sits on the roof (You better have some helping hands wrestling the 90 lbs. on the ladder up the roof) and the ceiling assembly with the air vents and controls for the AC.
The rooftop init is held in place with a square bracket which you need to bolt from the inside of your van. You’ll need to build some kind of support from the inside between the sheet metal and the bracket as the whole setup requires about 1.5″ distance between the two. I’ve used some Red Oak Plywood that I’ve painted with Polyurethane to protect it from soaking up humidity. Others welded metal structures for that. Just look at below picture to get an idea how the assembled thing looks like.
The plywood goes in between both structural pillars on the roof to add some additional support to the roof. You still have 90 additional pounds on the roof and you don’t want to end up with a dent in your roof due to the weight of the AC unit.
What’s left is to install the power line and the ceiling assembly with the air vents and controls and you’re good to go. Once I’m done with the paneling on the inside of my Van, I’ll post a picture of the final result.
Results
Do you really need a real AC unit? Yes and No 🙂 It’s definitely nice to have one when you camp in really hot weather where it doesn’t cool down much at night (the wife will be happy!) but you don’t really need it most of the time. We recently went on a 5,000 mile trip and used the rear AC exactly for one night in a Texas State Park to cool down the van for an hour or so before going to bed. The rest of the trip we spend in cooler weather up north so the fan that we also have on the roof was enough to keep the temperature down inside. But I’m sure on one of the next trips (perhaps Florida?) we’ll be happy to have the Coleman AC unit with us.
Parts needed:
- Rooftop A/C unit. You can find a good selection of units on eBay
, Amazon
or specialized online stores like AdventureRV.net (where I got mine).
- some leftover plywood for the frame
Tools required:
- Jigsaw with a metal cutting blade
- Drill with drill bit
- screwdriver
- wrenches
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Summary
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Technical Difficulty - 4/104/10
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Time needed - 4/104/10
I am working to do the very same thing. Only, mine is my 2015 passenger van. Can you tell me about the roof ribs. Did they bother the installation in getting the unit clamped down properly to make the gasket seal around the hole? Thanks.
Check my build for a roof top air conditioner install on an NCV3 Sprinter:
http://sprinter-source.com/forum/showthread.php?t=27822
very nice build thread! I’ve read through the whole thread when researching how to mount the fan and the A/C but then decided to go with plywood instead of metal.
Can I cut the roof seam and be ok?
Hi Gerald,
I can only assume that the roof layout in your 2015 NCV3 is similar to my T1N and if this is the case you shouldn’t have any issues fitting a standard rooftop A/C. You don’t need much more space than the 14″x14″ hole, perhaps two inches on each side to have enough metal for the clamp to hold properly. In my case I cut the whole pretty much in the middle between two ribs and there are no issues at all.
Or are you talking about the stamped “fins” in the sheet metal? they are no issue at all since the gasket that is on the AC unit itself is probably three inches thick and compressing the whole thing with the clamp closes all gaps. I didn’t apply any additional caulking and have no water coming in. First night camping with the freshly installed unit on top we had a thunderstorm with heavy rainfall and nothing was leaking.
Power usage?
Here’s the power specifications:
Cooling Amps-High: 15.3
Running Watts Standard: 1599
Running Watts Desert: 1913
Locked Rotor Amps: 63
Thanks.
Soft start capcitor unit will lower the locked rotor requirement.
What is the total width of solar panels? I notice the ac unit is centered. What is the measurement of the wood to the opening of the hole. Looks to be 3″
each solar panel is 47″ x 21″. Do you mean the thickness of the plywood? I used a 3/4″ and 1/2″ plywood to build the frame. The AC unit is centered but the exact location from the back was given by the width of the solar panels.
Where the wire is hanging out to the roof support. What is the distance from wood against support to opening?
do you know if a honda eu2000 will power this?
I never really looked into running the AC with an external generator but it doesn’t look like the Honda EU2000 would be powerful enough. The Coleman Unit is pulling close to 16 Amps when running on high but the amperage at start (locked rotor Amps) is much higher – spec says 63 amps.
What companies in Atlanta will install a Coleman unit owned by you.
According to this guy’s testing, the honda eu2000 will run a 15k btu A/C but will not start the compressor without the EasyStart 364 soft starter or something like it:
https://www.youtube.com/watch?v=zwI_GmtNdZQ
I just bought a 10 seater transport Freightliner. 2014. It has what I believe is a factory roof top A.C. unit on top. Does it run indepently from the unit in the cab. Will it run off the battery alone ? I have a SERVICE DOG.Her life depends on it. Does the engine have to be running or just w/the ignition ON ?
Hi Richard,
no – also the rear AC requires the engine to run to operate the AC compressor for the back. Since the front AC is not capable to cool down the whole van, Mercedes just added a second unit in the back. So don’t leave your dog in the van when it’s hot outside. You could install an aftermarket AC unit (like the one described in this post) and use a generator to power the AC while the engine is off. Batteries alone won’t work reliably.
So, I have been pursuing the install of an AC unit, like yours, but in a 12 volt, “engine-off” system, with a large battery bank, inverter/charger, isolator, all tied to my 14v 220 Ahr alternator, etc… It’s proving to be a challenge to find solutions and experienced dealers to assist me. I know I can cut my hole and mount an AC unit on top of the roof, no issues with this part. What I don’t know how to do is hook up the electrical part, like how to tie the wires into a breaker box and make a cord for shore power. Do I need an inverter for this? Do you have pictures and explanations of how you accomplished this part on your install? I would greatly appreciate some guidance. I will likely just stick with they way you did yours, and use a generator, like a Honda EU 2000.
Thanks!
Frank, did you get the job done? I can be of help. I have the setup that you are looking for.
Hello Frank,
How did the 12V Air conditioning system work ? If you thought it went well, Could youu provide some details ? What is Make/Model P/N and any other details?
Did the solar setup work? I figure at least 6-8Hrs run time for the AC in the van.
Hi Thomas,
I’m about to embark on the same ac install and was wondering if you could answer a few questions:
1. What thickness is the plywood? 3/4″ (two layers)?
2. Did you glue the plywood to the roof? What did you use?
3. Did you use screws running parallel to the floor through the vans support ribs into the plywood?
Thanks
Sorry one more question.
I’m going to order my unit from Camping World, what comes with the unit? Does it come with a foam gasket? I have read that this gasket is large enough to absorb the bumps on the roof making the external part of the install easy.
How can I remove a rear AC compressor from my 2000 Sprinter? It no longer works and I would like to use the space for storage.
How did you fasten the Red Oak Plywood bracket to the van? I see that its centered between structural pillars, but whats holding it…..
it’s glued to the panels.
Your AC unit is too close to your solar panels! Any shadow cast from the AC unit to the solar panels will significantly reduce the output of the panel. Your panels appear to be monocrystalline, – better than polycrystalline panels, but even monocrystalline panels take a huge hit from even a couple cells being in a shadow. The cell(s) in a shadow not only dont put any power out, but they act as resistors and so it blocks current from all cells in that row/column (really depends on how the individual cells are wired up in the panel). I suggest moving the front panel to the other side of the AC unit.
Also, would love to see the interior pics of the AC unit!
Thanks!
thanks for the tip – I check what I can do with moving the panels around. I’ll update the A/C post as soon as possible with more pics.
I know this thread is +2 years old. I wouldn’t sweat this issue. If you want to be anal retentive about those last few watts, park the rear of the vehicle facing south to minimize shadowing. Excellent work—mechanicals, electricals, interior, general ‘big picture’ planning. Everything.
Or just add another panel in front
where did you buy the solar panels? Thank you. Enjoying this thread!
I bought them on eBay and they shipped directly from Renogy
I am looking to buy a 2005 Sprinter and interested in installing an AC in the rear. I will be using this van as a mobile construction office. I do not know if I will always have power to plug into like what you would use in a camper. Unwanted to see if you could offer any advice on what I should be looking for….
look for a gas powered generator if you don’t have shore power available all the time. running these A/C units on batteries require more batteries than you really want to drive around on a daily basis.
Where did you find the 12v a/c? I haven’t had any luck. Thanks!
Hi Jamie,
Am also looking for a 12V AC, Did you find something?
appreciate your feedback.
Thanks
What was the effect on your mileage with the addition of the AC?
I didn’t see any change in mileage after installing the AC on the roof.
I am running an old 11.5K btu 120VAC rooftop a/c unit that came wirh this old Forest River Conversion 2003 Sprinter 2500 high roof longest wheelbase. The dash unit is wholly inadequate in the Deep South so I replaced the oem 12VDC alternator with a high output 270A 6 phase unit, typically used on ambulance conversions. Then using a 5,000 watt modiifed sinewave inverter, I am able to use the rooftop with the engine running. A smooth start capacitor (not required) would allow or a 3,000 watt inverter to be used. I have two 107 Ah hybrid deep cycle batteries in a house bank that allows the a/c to run without the engine for 30-45 minutes (depending on outside air temp, a/c setting, battery charge). I also had a 2,500 watt Onan genset that I can power when boondocking.
Thanks for the info!
Nice post man. Putting my Dometic Brisk II with Electric Heat on as soon as it arrives. I have no welder so polyurethane on wood will do I think.
Does gluing plywood between the ribs add enough support? I can’t wrap my mind around that yet.
The roof is strong enough to hold the AC unit. The plywood was just to have something sturdier for the bracing on the inside.
What do you use to power it?
It only works when we’re plugged into shore power as the power draw is to big for the inverter and battery setup.
I’m looking at “converting” the factory rooftop air conditioner on a friend’s 2500 Passenger Van so it can run on 12V DC while driving and on 120V AC when there’s access to “shore power” or a generator.
I see some conversation above on that subject but nothing conclusive about how to do it.
Does anyone have any intel from a successful conversion like that?