Fan-tastic vent in the window?

[etbadger]

Another option to consider is to rewire the dash fan to run even when the engine is off. We just crack a window at the back end of the van and turn the fan on low for ventilation when desired. To get a larger range of speeds we replaced the primitive resistor bank speed control with a ~20A PWM motor control for smooth speed adjustment, and pulled power from the house battery by splicing in where the fan relay sits in the relay/fuse box.

This doesn't require any new holes in the van, and the motor is already plumbed in.

-e

[zuren]

Originally Posted by etbadger

Another option to consider is to rewire the dash fan to run even when the engine is off. We just crack a window at the back end of the van and turn the fan on low for ventilation when desired. To get a larger range of speeds we replaced the primitive resistor bank speed control with a ~20A PWM motor control for smooth speed adjustment, and pulled power from the house battery by splicing in where the fan relay sits in the relay/fuse box.

This doesn't require any new holes in the van, and the motor is already plumbed in.

-e

I just took a look at your website - do you have a write-up and/or pics of how you did this?

My van has the dual fan/heater setup (one in the dash, one in the rear driver-side corner). Access to this rear unit is very easy and the vents are in the "living" area of the van so maybe I could look into wiring this unit up. I also just bought a Group 31 battery this weekend to function as my house battery. I'm getting my battery location and wires sorted out so I could certainly look into doing this at the same time.

How many amps does your fan draw?

[etbadger]

Originally Posted by zuren

I just took a look at your website - do you have a write-up and/or pics of how you did this?

My van has the dual fan/heater setup (one in the dash, one in the rear driver-side corner). Access to this rear unit is very easy and the vents are in the "living" area of the van so maybe I could look into wiring this unit up. I also just bought a Group 31 battery this weekend to function as my house battery. I'm getting my battery location and wires sorted out so I could certainly look into doing this at the same time.

How many amps does your fan draw?

I don't have a writeup or pics up yet. Two toddlers running around tend to reduce my time to work on the web-site.

The fan is the stock dash fan and draws about 24 amps at full tilt (quite a bit), but will run with enough flow to keep the van cooled off in the sun at about 5 amps (~60 watts), which is usually when our solar panels are putting out lots of juice, so we have plenty to spare.

The PWM speed control is this one http://www.electronickits.com/kit/co...or/CKMX066.htm but the variable frequency option may be quieter at higher frequencies (this one induces a hum in the motor coils when the fan is not stopped or full-speed, not audible when driving, but could be bothersome when stopped to some). I just pulled the variable resistor off of the circuit board, and replaced the dash fan speed switch with it. Power is supplied by removing the fan relay and plugging a house-battery circuit wire into the relay's old output terminal socket in the relay box.

I think I have some pictures somewhere and will try to get it written up soon. We used this all the past summer and it has been working well. Previously we had a big muffin fan that we would put in a window, but this is much less hassle.

-e

[WVvan]

The PWM control for the stock fan is a most excellent idea. Kudos.
Do you have any radio interference issues? I've read that the closer you can mount the control module to the motor the better (radio interference wise).

[Silver350]

How about using a Radiator fan and a Thermocoupler to regulate it? I used that combination to cool an air cooled Generator mounted in an aluminum box. It worked well.

[zuren]

Originally Posted by etbadger

I don't have a writeup or pics up yet. Two toddlers running around tend to reduce my time to work on the web-site.

The fan is the stock dash fan and draws about 24 amps at full tilt (quite a bit), but will run with enough flow to keep the van cooled off in the sun at about 5 amps (~60 watts), which is usually when our solar panels are putting out lots of juice, so we have plenty to spare.

The PWM speed control is this one http://www.electronickits.com/kit/co...or/CKMX066.htm but the variable frequency option may be quieter at higher frequencies (this one induces a hum in the motor coils when the fan is not stopped or full-speed, not audible when driving, but could be bothersome when stopped to some). I just pulled the variable resistor off of the circuit board, and replaced the dash fan speed switch with it. Power is supplied by removing the fan relay and plugging a house-battery circuit wire into the relay's old output terminal socket in the relay box.

I think I have some pictures somewhere and will try to get it written up soon. We used this all the past summer and it has been working well. Previously we had a big muffin fan that we would put in a window, but this is much less hassle.

-e

I'm back to revisit this. Do you use the factory van controls when driving down the road or is operation of the fan completely through the PMW now?

This is the factory setup in my van:

- van has both front and rear heater/AC/fan units
- typical climate controls for the front are mounted in the dash
- Climate controls for the rear unit are mounted overhead (above the rearview mirror)

I would like to retain full function of the rear unit through the front controls as well as have a PMW wired in and mounted in the rear to control it when parked. Due to my limited knowledge with this, I'm not sure if what I want is possible.

Thanks!

[LenS]

The PWM speed control could also work as a light dimmer on 12v DC lighting???

[zuren]

Originally Posted by LenS

The PWM speed control could also work as a light dimmer on 12v DC lighting???

I would think that a 12v rheostat (similar to what most vehicles have in the dash to control illumination) would be the easiest choice for lighting.

[etbadger]

Originally Posted by zuren

I'm back to revisit this. Do you use the factory van controls when driving down the road or is operation of the fan completely through the PMW now?

The fan is operated just through the PWM speed control. I removed the speed switch in the dash and replaced it with the potentiometer that controls the speed-control. It looks identical, but the fan-speed dial is continuously-variable in operation.

I don't have a rear climate system, so I have no idea how it is wired in, though I would assume the circuitry is very similar and could be controlled by the same or an identical speed-control.

A PWM control could be used for 12v lighting, however not most fluorescent lights. LEDs would flicker an awful lot, and for incandescent you would want a PWM supply with sufficiently high frequency to not result in noticeable flicker (would burn out the bulbs pretty quickly).

-e

[LenS]

Originally Posted by zuren

I would think that a 12v rheostat (similar to what most vehicles have in the dash to control illumination) would be the easiest choice for lighting.

My concern is not only amount of light but house battery power consumption. A rheostat would dim the lights but not save any (or very little) power. A PWM could make it possible to match the amount of lighting to the task being done and saving house battery power while doing it.

My present method: Each incandescent light fixture has two bulbs, one 20w and one 5w or 10w. I can switch between low (5/10w) lighting or high (25w/30w) lighting. If I wanted to rewire for a PWM I basically could have variable lighting between 0w to 40w per fixture and power comsumption that matched.

Just an idea