Camper van ventilation without using window vents or cutting holes (first see comment by @drewcress)

Cheap, stealthy, no-build, campervan ventilation. Here I figure out how to run the minivan's own blower fan to bring in fresh air all night. The trick is getting it to work completely disconnected from the van to ensure the car battery isn't dead in the morning.
PWM square wave signal generator: amzn.to/3APeAG1
18V Ryobi adapter with 12V step-down converter: amzn.to/3ZaniIc
40V Ryobi adapter with 12V step-down converter: amzn.to/3YRrkUM
Oscilloscope: amzn.to/3Octn0v
Lever wire connectors: amzn.to/3OexLMD
Smoke machine: amzn.to/3ZdRbaR
Fog juice: amzn.to/48TDIIg
Anemometer: amzn.to/40QWaza
Multimeter: amzn.to/4fur8Sd
Maxxfan: amzn.to/4fTckMM
*Sadly, those are not affiliate links. My Amazon Associate application got rejected because I don't have enough subscribers.

[@drewcress]

I appreciated the effort here but a hidden issue with this approach is most vehicles actually switch to recirculating air as the car turns off. The fresh air inlet is closed to help prevent dust, moisture, and rodent ingress. I spent a fair bit of time figuring out to get both the servo and fan to behave but it gets much more complex as a tap can change the starting position of the servo and break things when the car turns back on. I've tried other ways like a second battery just for car aux power (works) but ultimately the power consumption is just to high to make it worth the effort. What work a bit better is to take a small blower fan and point it out the cabin pressure flap (where the smoke exits). It's non destructive and the difference in pressure will pull fresh air in. However, it's a very small exchange when the van is otherwise closed up.

[@SemiSeriousLabs]

Thank you for sharing! Just to be 100% sure of my own setup, I just now did a smoke test. I put the machine under the hood and confirmed smoke came in through the vents with my battery-operated setup running. So I'm ok, at least, but I wish we had an easy way to tell which vehicles close their air inlets as they turn off. Out of curiosity, did your tests also use a three-wire blower fan? If not, and you had a two-wire type, can you tell us what voltage range worked best and how you controlled the voltage?

[@drewcress]

​@@SemiSeriousLabs Interesting! Glad to hear your setup is working as expected. I was a bit disappointed to find the Gen2 Toyota Sienna was more limiting. An aside, but I'm just now noticing much more vertical your air inlet is on the Gen3. Perhaps Toyota came up with a better overall design there given the trouble the Gen2 had with the climate control servos. Maybe Toyota opeted for a bit of an air mixer setting by default too? I could see some upsides to that alongside a more vertical inlet. As for more exact numbers, I'm afraid I'm not much use there. I was looking if it might work on multiple vehicles at the time and just doing some preliminary testing. It was mostly with a small 12v battery and a pwm controller with a dail, precise it was not. The vehicles in question didn't have a climate control system and their default adjustments where just some resistive elements (hints the silly high power consumption via the aux power approach). All of the vehicle (Express, Promaster, Sienna) did have a recirculation servo that defaulted to internal air when off though. After my testing and a bit more reading, I believed that was generally going to be the case / challenge on nearly all vehicles since the early 90s and onward. Nice to know that isn't so with some newer models with more well adjusted climate controls system. I'll need to do some more reading to understand exactly when and how they differ. Thank you for your video and your testing!

[@ericcamolinos3740]

I think the recirc flap closing with the car off is only common on older vacuum controlled systems, as there's no vac to hold it open when the engine is off.

[@drewcress]

​@@ericcamolinos3740 It seems nearly all 90s+ and newer servo based systems do this a deliberate feature as well. I'm having trouble finding a modern passenger car that doesn't do this but the lack of a feature isn't the easiest thing to hunt down. I'm still looking, but I've found some hybrid cars use an AC system that can air mix though it still unclear exactly how these behave when the vehicle is off. I did find a couple of RV systems that allow the fresh air intake to be open when the vehicle is off, but those appear to have been dropped in favor of the lower power rooftop options. So far, I think most adaptations of the above approach would need to disconnect the recirc servo from the climate control / computer and just run it manually via a separate battery and switch for best result. I do want the approach to work simply for elegance of the solution, but at that point, there are cheaper and easier options available as well.

[@SemiSeriousLabs]

@drewcress @ericcamolinos3740 I'd feel bad if someone went down this path on a car with a closed recirculation flap. So, I edited the title to help them see this discussion. Thanks again you two!

[@ontheroadwithtenzin]

I have a converted Dodge Grand Caravan. My approach is simple. I have good rainguards on the four main windows. I crack to kittycorner windows based on the direction the breeze is coming from. I lower the windows to just above the bottom edge of the rainguard. I have window insulation that will fold down the and allow air to pass thru. If I need more air I clip a good USB C rechargeable fan to the front row seatbelt and one to the opposite cross corner area. I don't remember where I heard this but you need 6sq inches of open window for ventilation when staying in a mini van. Doing this I do not get cold, there is no moisture buildup on the inside, rain does not get in and no one can see the windows are cracked open. Been doing it for years with no issue. And I have bug screens. Easy peasy.

[@montanadan2524]

As an electronics engineer, I found the approach interesting but it reinforced my approach of just cracking the window.

[@nestogonzo1]

Nicely done, I like the car camping idea so I went hybrid...

[@CharlesReedPi]

Me and my son are going to breathe all the air in this vehicle,* Child Services listens closely*

[@markmcla]

Very clever! I never thought of that solution to air circulation. Thanks for sharing! -On my 2007 toyota sienna minivan, I cut a hole near the rear of the vehicle on the driver's side. And then I cut a hole in the roof for one of those 6" mushroom vent fans. These holes provide a path for air circulation and it works well. And I can cover all of the windows. -But, like you pointed out, I had to make permanent modifications. I'm not worried about permanent modifications because my minivan is 17 yrs old. And if I ever sell it, then I'll just sell it as a minivan camper. I posted a video on my minivan camper on my channel.

[@SemiSeriousLabs]

Nice. I'm jealous of your heater. Cool how it has a heat exchanger instead of burning the same air you are breathing, like my Buddy Heater does unfortunately.

[@markeh1971]

Hi, it’s a good idea to use the existing OE,fans, ducting and filtration all provided FOC. Most motors are PWM driven now so it’s just packaging and powering the unit. I have seen a video where for stealth he put PC fans in the rear door posts and sucked the air out that way, venting down the post to the ground, using existing air path. You need air flow but might not want bloody big vent on top of your roof showing it’s a camper! Good video, take care M.

[@lightdark00]

Wow, adding to the great ideas for stealth. The only addition would be for less battery usage is for it to cycle on and off, allowing the CO2 to get in the 800-1000 range to not cool things excessively in the winter.

[@loughkb]

Hey that's pretty smart. And I'll bet you on the lowest setting, it's moving enough air to keep you ventilated. It doesn't take much air movement. Now you need to find the female connector and make a y assembly, then you can build it all into a nice little box that you stick somewhere out of the way but accessible.

[@andylewis4695]

Much better than cutting a hole. If you used an arduino for the PWM signal than you could also have the fan on a timer for something like 2 min on, 10 off. Also, if you put in a few diodes on the oem side and the homebrew side, than you should be able to leave it all connected all of the time.

[@Chris-ut6eq]

Good info, good testing and like any design solution there are always trade-offs. Something to consider, the max air fan type is made to move air with little to no differential pressure while the car fan must overcome differential pressure to force some air into interior(through a tiny hole) which forces the air out the rear vent. For building IAQ, it is suggested that one person needs 10-20cfm to avoid stale air.

[@EngineerK]

Was waiting for the CO2 retest with the fan running... You could redesign your system with an esp32 microcontroller running Esphome plus a CO2 sensor and relay. Can probably do the pwm on the microcontroller. That's if you really want to geek out 😂

[@max7w311]

May I have some advice on how to do this. I have an arduino microcontroller but heard better things about esp.

[@EngineerK]

​@@max7w311 lots of info on the Esphome website. It's very easy to integrate esphome devices into home assistant. You can do a good chunk of the automation work on the device but generally speaking this is easier to do in HA (in other words, just use the Esp to collect the data, automate against the data in HA but that being said you can run an Esp device with automation autonomously).

[@DustyyNomad]

Brilliant idea! Ive wondered if this would be possible and have never seen anyone pull it off until now. Great video!

[@konserv]

For PWM you can also use cheap $1 servo tester. It should also work. This type of control signal is everywhere - from servos in RC hobby and computer fans to cars and literally almost every variable speed fan in any equipment.

[@konserv]

And hooking up something like "webasto thermo top evo 5 petrol" for gasoline cars or any other diesel parking heater for diesel car/van is reasonably stealthy, compact and integrated.

[@SemiSeriousLabs]

I would LOVE a Webasto heater. Someday... for now I'm going to get a winter sleeping bag.

[@rhiantaylor3446]

I always thought this was the best approach but for different reasons - just want to keep the roof completely clear for solar cells. Next challenge is to get the A/C running without the engine..... By the way, don't you need to interpose a diode (a beefy schottky diode) in the main 12v feed to the fan so you can power it without removing the wiring loom plug or back-feeding into the rest of the ignition circuit.

[@SemiSeriousLabs]

Interesting idea!

[@wilsonwombat3456]

I have a pop up sink waste in the step well; a muller vent on the roof and underneath a noctua 12f fan(0.07a) with a variable switch. Max air exhaust about 7 litres per minute.

[@stephenlabarre7890]

I haven't even finished watching the video and I'm impressed with your logic/knowledge. Thanks. It gets me thinking about things I might explore.

[@firstnamelastname2669]

This makes me wonder why manufacturers don't make this a feature for dog owners. Leaving a window open isn't why secure.

[@ThisisForTheTV]

2010 2015 Prius solar would run the HVAC blower off the solar panel to keep temperatures within reason. Not really for pets but idea and technology is there, they just don't. It also had a button on the remote to turn on the air conditioner remotely.

[@mattmccallum2879]

This was amazing! I’ve only seen one other person do something like this…tempting for not having to drill a big hole in the roof for sure!

[@alecmorrow3764]

Hello! The detail you go into is amazing. I am in my 2008 Sienna and thinking this would be a great idea. I just checked and have one of the wiring harnesses with 2 leads. Do you think the speed knob acts and a potentiometer and my blower accepts steady DC (with no PWM)? Would you expect my blower input to be 5V or 12V. Thanks for your time!

[@SemiSeriousLabs]

Hey, I just found a very helpful demonstration: kzbin.info/www/bejne/gZu0YYOBec6Fetk It looks like the lowest speed setting in his example is 5V. That or else 6V should be pretty easy to find in battery sizes.

[@WeirdOneOz]

Great idea thanks for going to the effort of testing it all.

[@WalterPidgeonsForge]

I used a bilge blower for boats… and installed it next to the spare tire Since it was easy to attach flexible ducting and used a round, screened soffit vent with a screen from HD.

[@SemiSeriousLabs]

Cool! I had to look up what a bilge blower was, and they do look useful for a variety of setups.

[@testi2025]

Most car HVAC systems have a simple 12v input for auxiliary fuel heater like Webasto. So in most cases you need a simple switch. Just look up electrical drawings of your car and you should find it. These auxiliary heaters are popular in Scandinavia.

[@ssteele1812]

Could you replace the ryobi battery and voltage converter with a portable power station with 12v out? I know you were using what you had on hand. Im just curiousif you could get more run time and use somwthing that some van dwellers have on hand.

[@SemiSeriousLabs]

Yes, and that would be better. I know some of my power gets lost during the voltage step down stage, and yours wouldn't need that.

[@vinnyandrocky]

Good to know the air exit at the back. If we crack the front window open, it will affect the air path. So we need to close the front windows to make it works? Nice video, subscribed.

[@EvanBlack11]

Would this same items work with a Caravan?

[@SemiSeriousLabs]

Not exactly. It looks like most years of Caravan use a blower motor resistor instead of controlling it with pulses. That means your motor only has two wires and should be really simple to run. But what's the easiest way to run it at low speed? Maybe try running it directly with 5 volts, which is easy to get from a USB power bank.

[@EvanBlack11]

@@SemiSeriousLabs Brah this is prob the most helpful YT reply I ever gotten thanks. 🙏🏽

[@z6006]

Nice work man. I'm going to see what else you're up to in your other videos

[@awesomearizona-dino]

Good work, ive run into similar issue with modern radiator fans, i may try your experiment.

[@sbrownproductions]

Does that PWM pulse at 5V or does it pass through the voltage from the VDC source? I know you found 5V on the pulse, but I don't see dropping anything to 5VDC...

[@SemiSeriousLabs]

Good catch. I shouldn't have assumed the output was 5V. The output is the same as the input voltage. So maybe adding a resistor would be safer.

[@MYYTVI]

Finally someone did it! Have been thinking of the same solution! Thanks brother! 🤘

[@MYYTVI]

You could have done an air quality test with a fan on to determine the lowest setting for the fan to maintain air quality. 😉

[@ItchyKneeSon]

You could add those screens permanently to both back pop-out windows. Add curtains for stealth.

[@tybrady4598]

Man, thanks for the CO2 info. I wrongfully assumed my van would naturally circulate a tiny bit of air through the vents. Your meter shows otherwise. Plus another comment on here made a good point that many vans close the vent flap to prevent bugs dirt and rodents from getting in when the vehicle is off. I have been cracking my windows, but I see I might need more than that. I’m gonna buy CO2 monitor.

[@mlisaj1111]

Agree, though I don’t think most vehicles are air-tight enough to make people pass out. I am no expert, but seems like there would be many cases of it from people sleeping in cars, or that it would be a risk when driving. But higher CO2 will definitely cause some symptoms, like feeling tired or groggy, headaches in some, etc.

[@BoopSnoot]

If you are talking about the exit flap, its a simple one way valve. Something from outside pushing in can't get in, it can only be pushed out to release air and it does so passively. If you mean on the intake, seems odd it would need to considering that there is a cabin air filter in the way before the air gets inside the vehicle one way or another and it traps debris.

[@benels54ven45]

I once tested the energyconsumption of a car-fan . On full speed it was about 140 watts..... way too much

[@motorenbastler9289]

I installed a complete car ventilation box into my camper. I was worried it would pull too much energy so i was afraid of using it. Since i have my Victron Solar charger i could figure out it pulls 30 watts on first fan stage. this way i could run it for 30 hours on my 100ah Lifepo battery and 15 hours on a lead acid battery.

[@BobHill-s2c]

Good video, no blubber. However, if you're living in a van, charging the 40V somewhere everyday is pesky.

[@Ratsnacker]

Great idea. Thanks for sharing!

[@hejasverigeee]

Been looking for exactly this solution! Greetings from Stockholm Sweden Europe 🇸🇪♥️

[@crissgen]

Thanks , was very interesting, even if I didn’t understand, i bought a liteAce van , I will just open the engine access by the passenger seat 😂

[@OdysseyCamper]

Clever! I cut dual holes in the floor with 275 CFM bilge fans w/speed control. In hot weather, one serves as a vent for the AC unit. In the extreme cold, it is the intake for a diesel heater. But yours might be the most clever I’ve seen. Subbed

[@thelegion_within]

that's a really neat hack!

[@SuperADI2]

Thank you for the video, very useful information s 👍👍👍

[@p.newsman]

🏆 McGyver certified! 👌😅

[@justcommenting4981]

Are you an electrician or mechanic by trade?

[@fransubaru]

Very interesting idea!

[@gdlerner]

I don t have this problems I drive a defender 110 many holes everywhere😁

[@lastresort1757]

There’s no way someone is dumb enough to think you can “breath out” all the air in a van. Vans are not fully air tight, no vehicle is

[@jamesphillips2285]

From USDA Food Safety and Inspection Service "Carbon Dioxide Health Hazard Information Sheet": "The American Conference of Governmental Industrial Hygienists (ACGIH) recommends an 8- hour TWA Threshold Limit Value (TLV) of 5,000 ppm and a Ceiling exposure limit (not to be exceeded) of 30,000 ppm for a 10-minute period. A value of 40,000 is considered immediately dangerous to life and health (IDLH value)." Pretty sure I can reach the 8hour exposure limit threshold within one hour of sitting in my car. My CO2 meter is not designed to read any higher than 5000PPM.

[@CoastGord]

Interesting info...

[@nyrubin]

I've slept in my car for 8 hours once, didn't run out of oxygen

[@ipsylon7297]

Smart.

[@jfloydsea]

Find a female gender plug and build a y-splitter so you don’t have to swap plugs constantly.

[@avamaria8447]

I'll stay with cracking the windows

[@nyrubin]

Now can you do another video where u hack the AC and run it off a power station lmap

[@HesamSimin]

great

[@RA-II]

Your car is NOT air tight.

[@peteroffpist1621]

Buy a Tesla, Tesla has camper or dog mode. Climate control nice and warm in winter or cold and fresh air all night long in the summer.

[@veganpotterthevegan]

Window covers aren't stealthy either. Everyone knows when someone is sleeping in a car. Just park where you're allowed to park/sleep overnight.

[@loveasapologetics]

TLDR: uses vehicle’s manufactured exhaust/AC feature with auxiliary power or power monitoring.

[@topcheese2889]

Or just crack the window

[@remog38]

So intersting thanks

[@wompstopm123]

what is a dude that already has kids doing stealth van camping? did you get divorced and your wife got the house ?

[@NoelG-IRE]

Adding a roof vent to a van adds value. Don’t know why you think it’s destructive and somehow reduces the value. If it’s done right it’s fantastic. Even a basic roof vent without a fan would be better than pulling half the dashboard apart and ordering a heap of special parts to make it work. Just because you can, doesn’t mean you should. Will your version work? Yes. Is it a good solution? Absolutely not. Glad you posted it though as it is a good deterrent for others not to try it.