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HVAC blower speeds and heater blower resistor trouble

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Offline AJMBLAZER

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HVAC blower speeds and heater blower resistor trouble
« on: November 11, 2007, 10:31:42 AM »
So I've been dealing with this a while and made some headway today...but not really.

My HVAC system only blows on the highest setting.  Set it to one of the first three settings and it does nothing.  Flip it all the way to the right on the highest setting and it blows fine for as long as you can stand the heat.

I was told it was the heater blower resistor that is on top of the heater box.  I've attached a picture.  A member here was good enough to send me one they had sitting around but I've found that the condition is the same with either resistor.
However both are used and the solder on the springs/coils on both is cracked and crumbling.

Do I have a problem with something else or should I spend the $21-32 on a new resistor and try again?
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Offline sidekicksrock

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Re: HVAC blower speeds and heater blower resistor trouble
« Reply #1 on: November 11, 2007, 01:37:19 PM »
I don't know what that little black thingy is, but what you are looking for is somewhere along the wiring between the switch and the blower motor. It will have 3 or 4 wires in and one wire out it will contain resisters on all but one of the wires. These resisters, cut down the voltage to the motor on the lower speeds and the high speed wire just runs 12V straight to the motor.
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Offline AJMBLAZER

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Re: HVAC blower speeds and heater blower resistor trouble
« Reply #2 on: November 11, 2007, 02:13:20 PM »
That would be those things in the picture.

Their official name is the Heater Blower Resistor.  Four pink wires going in and there's three coils on each.  It sits on top of the heater box in all that wiring.
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Ira

Re: HVAC blower speeds and heater blower resistor trouble
« Reply #3 on: November 11, 2007, 02:24:56 PM »
I have the same condition (95 Track), but there are FIVE blower settings, right? And on mine, the first three are dead, but the two highest are fine.

Remember--this can be a switch thing OR the coil resistor pack, which is located behind the glove compartment. I haven't bothered investigating this yet because I'm a total retard mechanics-wise, and where I live climate-wise, I've been able to live with this pain the ass.

But I DO want to fix it.

The thing is, I don't even know what the resistor pack even LOOKS like, but you're supposed to supposedly know it's bad just by looking at it. That you'll see it's burnt.

Pulling out the switch and cleaning it costs you nothing, although I don't know HOW you actually do that. I assume you just extract it from the dash (all wires still connected), and blast with air and WD 40 to clean.

I will be closely following your ultimate SUCCESS here closely, because I wanna fix mine too. SO PLEASE SHARE YOUR PROGRESS VIA PM'S WITH ME!







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Offline AJMBLAZER

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Re: HVAC blower speeds and heater blower resistor trouble
« Reply #4 on: November 11, 2007, 02:40:20 PM »
Well, 5 settings if you count the off setting all the way to the right.

Again, the resistor coil packs are the objects in my picture above.  Everyone can see them, right?

The pink wires in the first picture above go to the resistor.  It's held on by one Phillips head screw that is conveniently buried under all those wires in the picture.
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Offline Digger

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Re: HVAC blower speeds and heater blower resistor trouble
« Reply #5 on: November 11, 2007, 05:48:10 PM »
You can use a voltimeter with a resistance setting that measures ohms to check and see if either resistor pack is good. Just check the resistance from each pink wire through to the single output. There should be measurable resistance, but if the resistor is bad, it wont allow any current through at all.
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Offline pjs97talon

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Re: HVAC blower speeds and heater blower resistor trouble
« Reply #6 on: November 11, 2007, 08:54:47 PM »
Here's how the resisters work-
On "high" the blower motor gets 12 volts and runs at full speed. If you select another speed the power is routed through the resistor. The lower the setting on the switch- the more coils the power passes through on its way to the blower motor. (ie: low speed passes through all three coils dropping the power as it passes through each one. med low would only pass through two and med high would only pass through one)

The reason that the blower only works on high is because when you select high on the blower motor switch- it sends the current directly to the blower motor, bypassing the blower motor resistor pack. Since the resistor coils are mounted in the air duct (to help the disipate the heat generated) they are prone to corrosion. After they get corroded- the heat cycling causes them to become brittle. Once brittle- they break and then cause an open circuit and cause the blower motor not to work on any of the speeds that are sent through it.

In short- Get a new resistor. Be careful during instalation as not to damage any of the coils and you should be fine.
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Riddick

Re: HVAC blower speeds and heater blower resistor trouble
« Reply #7 on: November 28, 2007, 03:02:22 AM »
Is there a part # for this? I have googled the crap out of this but cannot see to locate.. Help please?
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Offline AJMBLAZER

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Re: HVAC blower speeds and heater blower resistor trouble
« Reply #8 on: November 28, 2007, 04:06:39 AM »
Go to www.rockauto.com and look it up under a Sidekick.  Should be under blower/heater or something like that.  For some reason they didn't list it under a Geo Tracker but did under the Suzuki...and one of the parts was AC Delco brand!
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Offline Skyhiranger

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Re: HVAC blower speeds and heater blower resistor trouble
« Reply #9 on: November 28, 2007, 06:07:35 AM »
Did you get this fixed?  It sounds like the resistor is not the problem.....sounds like a switch problem.  I have used resistors before that have the "solder" (the grey looking stuff on the coils) cracked and crumbling and they still work fine, as long as the coils aren't burnt in two and the solder (where the coils mount to the assembly) is still in good shape.
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Offline AJMBLAZER

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Re: HVAC blower speeds and heater blower resistor trouble
« Reply #10 on: November 28, 2007, 06:35:25 AM »
Nope, broke and busy.  Hopefully this paycheck tomorrow will have enough left over for a $25 switch. :P

I was given another resistor that looks worse than mine and both seem to do the same thing.  I'm betting it's the resistor.
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Offline AJMBLAZER

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Re: HVAC blower speeds and heater blower resistor trouble
« Reply #11 on: January 12, 2008, 02:14:01 PM »
Snow came and the temps dropped so I sort of forgot about this until a few weeks ago when the temperatures rose again.  Noticed on www.RockAuto.com they listed an AC Delco resistor for $2 more than their cheapest and $5 less than their most expensive so I figured why not and ordered it.  It was on backorder but the temps were dropping again so I haven't exactly been using the low fan speeds.
Resistor arrived this week and man there's a lot more solder on it than either of the two used ones I have.
Just plugged it in (can they run any more wires and looms through such a small a space?) and whalla, I have all four blower speeds again. 8)
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