Replace the stove vent motor with computer fan

Well last week my computer OS registry dumped (backed up your stuff recently??). Decided after a lot of work trying to restore to add new larger HD, hook up old hd as slave and start from there. So went looking for new HD, Anyway I'm standing there in the store-I REALLY don't want to do this... and on the top shelf I notice a whole shelf of cpu fans. Hmm, that's what Id rather be doing, Anyway after a week of reloading software, restoring directories I'm back up,. Though I wouldn't have chosen this route as an option, cpu is faster, cleaner and meaner.

On a trip back to the store to upgrade one of my programs I looked at the fans again. I started comparing the CFM ratings. Rather small-then I picked up one, three speed fan, rated 39/56/79 CFM, had led lights. Hmmm still kind low on CFM, but 79 might open the vent hood door. The leds would make some nice low power night lights....power consumption minimal- but will it actually pull enough air?..what the heck, so I picked it up. Its an Antec Tricool, 3 speed/3 led - 120x120mm.

Install:
Looking up underneath at the stove hood, I notice the fan box is separate, has 4 screws, cool- I wont have to pull the whole hood and all the wiring (our generator start switch hour.meter is also on hood face). After disconnecting the fan motor wires, remove the 4 screws- box wont come off?. what the heck I wrestle with it a while and finally resign to pulling the whole hood. Wiring wasn't that difficult, remove front panel, all the gen stuff was on a plug, the power in went to light switch and the other switches looped off it. Earth ground was on case screw. The incoming ground wire however was hard wired between the front panel, fan motor, went thru case to fan motor box. I just cut the incoming ground wire (used wire nut to reassemble). So only one wire required cutting most wires stay in place. Remove 4 large screws,drop hood , pull out wire loom, hood slide out. Nice

Take to shop to see what needs to be done to replace fan. Oh I also seen why the fan box wouldn't come off, It has tabs that go thru hood case and are bent over. You cant access after hood in installed. Why use tabs if it screws on-redundant makes removal impossible installed. Oh well , I could cut them off for future ease of working on the fan-but I'm going to seal the box to case so separation wouldn't be easy-and I guess tabs do hold the back of box against the back of case.

Above I've started the install. To remove the fan & motor: Mine the fan is just pressed on the motor shaft, a bit of effort and it just pulls off. 2 screws hold on motor. Unplug 2 wires, black on mine is hot. The case has a cross bar that held original motor. Looking at the pancake motor/fan I could easily make something to hold it that would screw to existing brace. There's enough room between brace and fan screen. I'll need to make a cover or something to make the opening smaller. Proceeding to use metal tape I seal all the edges/ holes inside the fan box. I want any air the fan pulls to go OUT and not back inside the camper, might help it push open the 2 flapper vent doors.

I realized I could just cover area of the metal screen to resize opening instead of making another cover. Then I realized the muffin fan could just sit on the screen instead of making a mount. The fan has a plug on wires if I need to remove. So I mounted the fan to screen, used metal tape to cover & seal the areas around it. I soldered the fan plug wires to back side of org motor wire terminals (in case I want to reinstall org motor). Covered in heat shrink. The fan has an extra plug for cpu monitoring -just wrapped &left on. The 3-speed switch for right now will just protrude from under screen. Its actually more of a selector than a constant use switch. It does not turn off the fan, only selects speed. Its wired to org motor wires, so existing vent switch turns on fan. If you need to change speed-you use the 3-speed switch. As I still don't know if this fan will work so this is how I mounted.

Above-I stood hood on side & closed the flap door, hooked up 12v, turned on the fan, at low speed it opened the door! COOL. The lights are really bright but are filtered thru the screen. Now that I know it works Ill reinstall the fan on the screen, Using a piece of disposable cutting board sheet material Ill cut hole size of fan, place on screen then mount fan to screen using wire ties. That way screen can be removed by unplugging the motor, undoing ties to remove fan and hole cover for washing. (in the years we've had this camper I think i washed screen once, course now that we may actually use fan, may need it more often :) The switch needs to be changed-dont know how long it will last . When/if I find somthing Ill cut off old switch, put a plug on motor leads and run to new switch. Again this isn't an on/off switch- 3 wires come from motor, one of the wires is hot (low speed), switch connects, I assume, the 2nd wire for medium, 3rd for high. Motor has 3 sets of windings, odd lil thing

Whoo Who! Snack light!-
Got hood remounted-it was dark so I got to test the lights, soft blue-it'll make for a nice midnight snackin light. When other lights are on you dont see the blue. But for the real test- will it open both the inner door and outer vent hood doors to extract air. Fan was in medium position, went outside- Wow, doors are open-its working, great. Tested on low, doors open. Im suprised, but.....as an added bonus, you should see the blue light from outside-ha I hadnt thought but when the fans on the led lights shine out the exterior hood. Looking at camper you see a strip of really bright blue glow, Pretty funny. So we've got a fan well be using, quite, low power draw & built in night light. I'm sure you could find other fans or multiples of smaller ones. Lots of options.
I did test old vs new motor, Old motor: initial startup 3.3 amps dropping to 1.5 stabilized in 3 sec, new motor @ low, mid & high respectively 0.1, 0.2 & 0.3 amps, no startup surge. Now I'm looking at the bathroom fan, though a bit more CFM. Maybe 3 or 4 of the small single speed - minus the leds (great glowing vent lids :)

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