Heater fan resistor solution

budgetzagato

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I've been looking for a solution to losing my Vanagon's front heater fan low/med speeds for a couple of months. As you may know, the resistor can fail leaving you with only the high speed. This is great for defrosting or cabin air exchange, but not so great for heating.

This same problem faced me for the Scorpion, as it was broken when I got my car. Finding one used or new has been a challenge.

I searched the stock shelves of my local NAPA (great folks who occasionally let me do stuff like this) and found a heater fan resistor that resembled the one in my Lancia Scorpion, a series of resistors in a metal cage NAPA part BR85, $6.95 with my AAA discount. I experimented with it in my Scorpion and figured out how to hook it up using the one fan speed still available.

To solve my Vanagon problem I made an approx. 8" harness of 12g wires that takes the power that goes to the switch as the high speed, and the other two speeds as two lower speeds, although you have a total of four speed options with this part. The resistor is nestled just to the right of my stereo/ashtray. This area seems pretty devoid of other wires etc. which is important as the resistors do get very hot, glowing actually. Normally the resistor is inside the heater fan housing or duct where the moving air helps keep it cool, so we'll see how it works. This will also work in my Scorpion who's resistor is also broken.

The hardest part is deciding which speeds to use, I opted for the upper 3 of the 4, the lowest speed seems pretty useless in the larger volume of the Vanagon. Might be good for the Scorpion though. :)
 
You might consider this solution:

http://store.qkits.com/moreinfo.cfm/MX033

More expensive but less heat and less energy actually used.

In regards to the Vanagon solution, I would be worried about the heat build up. The resister is in the airflow for a reason.

Karl
 
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Yup

I burned my finger on the resister from the X1/9, I had no idea what it was at the time. They need to be in an ope area or you will cause a fire.

Warren
 
I guess I should move it...

The wires are long enough to relocate it the other direction and have it be in the open where the hear comes out at one's feet (on my Vanagon). Or, I could have it on the dash as a cool retro display. :)
 
You might consider this solution:

http://store.qkits.com/moreinfo.cfm/MX033

More expensive but less heat and less energy actually used.

In regards to the Vanagon solution, I would be worried about the heat build up. The resister is in the airflow for a reason.

Karl


oooooh, I like that.
My fan won't kick in on medium unless I get lucky and jiggle the switch, If I go to high it works and then back to medium it usually works. Don't know if it's the switch or what. If I could mount this in that spot, (unlikely) that'd be cool, variable speed fan. Nice. Maybe elongate the knob shaft so the guts sit further back. I like it. Of course I'd have to somehow mount an LED in the knob......Bob has infected me.:sun:
 
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Okay, had to chime in

budgetzagato,

Has it been that long ago that resistor fried ? Seems like yesterday.

Congrats on your NAPA investigation !

At first I was thinking an extruded aluminum piece to surround that resistor. All sorts of standard shapes out here that would make a cool looking cooling fin arrangement and suck the heat right away from the component.

Then

"Hey, wait a minute"...how about going solid state ? 12v input - (3) port output of varying diminishing voltages. Mr. Brown ?

Then

"Hey, wait a minute....that fan motor obviously can run on several different voltages. Does the motor have three different windings ?

If it does not.....How about a rotary actuated variable resistor ?
Or a rotary actuated solid state component ?

i.e. swap out the single pole triple throw switch for that of a rotary type.

When you are done over there then you can come on over and help on some REAL WORK to a miniature fiat....:)

well1.jpg


I see there are some 'holidays' in the hard wax application that I'll have to recover tomorrow. Amazing what the camera captures that the eye cannot see.

Happiness is a prepped surface prior to component fitup.

out for now,
lezesig
'72 X 1/18
 
Variable voltage is a good idea,

But the suggestion made by K Mead is a "best" one if you do a slight modification. You can replace the potentiometer with a step switch. (as Lez suggests) Phase adjust of the DC is way more efficient and generates much less heat as opposed to a voltage dropping circuit.

Just pick the number of steps with a (step) switch of choice and divide the fan speeds to the number of steps. Simple procedure to do.

If you decide to go this way Greg, I'll help you out with it. Just let me know.
 
Man, I'd have killed to get a glowing resistor, or any kind of heat up in the front of my 80 vanagon when I lived in Omaha!:p I don't think that aircooled motor got over lukewarm up there in the winter!

Someone mentioned a rotary variable resister... those suckers can get COOKING HOT too... so if you went with one of those, make sure it's not overheating. The fan might be flowing more juice than a few interior lights for example.

I had the entire dash on my old Z/28 torn out once, dyeing it from faded red, to black... and had my light switch precariously perched ontop of the foot actuated parking brakes bracket... I reached down to turn off my lights and placed my finger tip on the coil of the variable resister for adjusting the interior lights. :mad2: My finger sizzled like a steak on a grill!
 
ballest resister

I used a ballest resister for a points style ignition system. Also changed the controls to touch sensitive LED switches.
 
Do you have a sharper image

of your switch console? Curious of what you used for touch switches.
 
led switches

They are made by "pilot", and sold in most chain automotive stores.the top pic is with the car ignition off. The second one is after turning the ignition on.the last shows how they look when switched on. This involved the use of a number of dual circuit relays and some small electric airvalves used to control vacuume flow to the various air flow controls.



 
Really well done Doug

Impressive job. Gotta give you credit for a well done job.
Thanks for the detailed photos.

I was looking at touch sensitive switches on evilbay and found others not quite like these.
These really compliment the console. Well done! :thumbsup:
 
thanks

it was alot of work. Each of the ten switches had to be shaved on it's side to get them all to fit! No fun.
 
Hope it works out for you, BZ.

Continuing OT - do you (dburdick) have a suggested source for electric airvalves? I need a variable bleed for my (vacuum controlled) heater control valve on the X1/9 - right now, it's on or off, no blend.
 
can't help you there

These too, are on or off. And because they hold vacuume so well, I have to use two of them to control one thing. I tie them into a dual circuit relay, so that when power is interepted to the relay, it then closes and opens one valve to bleed off the vacuume to allow the vent to close.
 
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