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

Would this same items work with a Caravan?

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!

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

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!

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.

Interesting info...

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

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.

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.

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.

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...

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

Very interesting idea!

So intersting thanks

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.

that's a really neat hack!

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

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 😂

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.

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

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.

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.

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.

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

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.

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.

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

I'll stay with cracking the windows

@SemiSeriousLabs I did a similar thing when I was away camping in my Lexus LX570 (200 Series Landcruiser) a few months ago, so I could control the car's ventilation fan using my phone while sleeping in the back.
Luckily, being a nerd, I took an ESP32 module with me (they are only a few dollars) in case I decided to control something while away on the road.
ESP32's are 3.3V, so I went to the local electronics shop (Jaycar here in Australia) and bought a 3.3 to 5V converter and a relay. I used the Arduino IDE and programmed the ESP32 to create the Pulse Width Modulated output to control the fan speed, and host a WiFi Captive Web Portal website. I powered the ESP from the USB power that I already have in the car. It only took about an hour to set up.
As shown here, the Toyota wiring is really easy to access. The White/black stripe and Black wires are battery power from the car and remains on even when the car is shut down, Therefore it only needs a PWM signal on the third small wire to make the fan run. I just cut the smaller signal wire and connected in the relay (Common contact to the fan side, N/C contact to the car's signal side). When the relay is off, the signal to the fan is connected as normal to the car's control module. Then connected the ESP32 output (via the 3.3 to 5V converter) the the relay N/O contact. The relay is also controlled by an output on the ESP32, so is also controlled with the phone on the website. When the relay is on, the PWM signal comes from the ESP32.
I just played around with the PWM values until I found out the required Duty Cycle. As the signal is generated by the ESP32, it can be inverted so that 0% to 100% setting on the Web Portal is 0 to 100% fan speed. I also set up a timer function so I could make it time out and not remain on after I'm awake.
My setup was still running off the car battery, however I have a 2nd battery in my car, so I wasn't too concerned about the battery being drained. I also have a Bluetooth monitor on the batteries, so I could also use my phone to look at the battery voltages and make sure it was OK after each night.
I found that you only need the fan just ticking over through the night to create heaps of fresh air and it barely had any effect on the battery. I thought about also setting my system up to only bring on the fan every 10 minutes, but didn't bother when I realised the battery was fine.
I intend to make a video of my setup eventually, but have been too busy since I got home.

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

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

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.

Your car is NOT air tight.

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.

Smart.

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

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

Are you an electrician or mechanic by trade?

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

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 😂

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.

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

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

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.