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Guest Subaroid

DagNabbit! Heater blower is toast! (to be archived)

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Guest Skip

Did anybody catch the Fuzzy Dice Theory?

 

Using a IC555 timer as an astable oscillator firing a FET ?

The three positions on the switch could be used for three resistance value to change the freq of the ocillator and thus the speed of the blower

 

Come on FD -kick it out mate

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Guest Fuzzy Dice

This is for you electronics geeks, you know who you are...A 555 timer/FET combo might work. Below is a link to a motor controller schematic I found...no sense in reinventing the wheel and designing somthing from scratch. Throw out a few of the extra parts listed, remove old coil resistors and mount the whole circuit in their place and bam...a cool little motor contoller. I see two challenges to overcome. First, you have to figure out a way to get a diode in parallel with the fan motor and second, I'm not sure there's a ground wire coming into that block (although you can route another wire for ground).

 

After reading the other posts it might just be easier to get some resistors from digi-tech and rig something in there. Possibly less hassle, maybe not as much fun though. I just think the oscillator/FET switch would be kinda fun...just gotta find the time. I'm still trying to find the resistor block in the car!

 

www.solorb.com/elect/solarcirc/pwm1/

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Guest Skip

Hey FD I like your idea of using a IC555 better

how about both guys named "Forrest" Mims and Cook

 

Hey shoot me an email and I'll get ya hooked up with where the block is.

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Guest Bill Putney

The multivibrator motor control is very good from most aspects - compact, easy to build, *very* efficient (produces little heat of its own). The one drawback, as someone mention earlier, is it creates RFI/EMI (radio frequency interference/electromagnetic interference). Overcome that problem, and it should work well.

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Guest edrach

Finding the resistor block: Remove the panel below the dash and in front (toward the engine) of the glove box. Look under the dash and see the blower motor. Forward of the blower motor and just a little to the left is the resistor assembly. Mounted with two phillips screws on the left and right of the assembly itself and with one of the mounting bolts (10 mm hex with phillips) on the blower plate. Get under there with a flashlight and you're sure to see it. You could follow the four wire cable down to the unit, but I'm too lazy to go to the garage and see the wire colors involved (mostly blue). Also, you might have to carefully remove the "corrugated" rubber tubing (about 1/2" in diameter) to see the assembly. You won't see the resistor coils until you remove the three phillips screws.

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Guest McBrat

This is the info from Ed...

----------------------------------------------------------

 

Resistance/Voltage readings on Block

 

Coils are in series. Smallest guage wire is coil A; coils B and C look about the same but about double the wire diameter.

 

&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp Coil A&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp Coil B&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp Coil C&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp Total

 

&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 1.1 ohm&nbsp &nbsp &nbsp &nbsp 0.9 ohm&nbsp &nbsp &nbsp &nbsp 0.7 ohm&nbsp &nbsp &nbsp &nbsp 2.7 ohm

(all resistance readings taken cold)

 

Speed 1 (lowest)&nbsp &nbsp &nbsp &nbsp 3.1V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 2.0V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 1.4V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 6.5V

 

Speed 2&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 0.3V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 3.0V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 2.0V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 5.2V

 

Speed 3&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 0.2V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 0.1V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 2.9V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 3.2V

 

Speed 4 (highest)&nbsp &nbsp &nbsp &nbsp 0.1V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 0.08V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 0.05V&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp 0.3V

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