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Old 11-22-2006, 07:23 PM
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Cheap GM HVAC blower motor fix.

I read this somewhere and had the same problem in my 2000 Impala, the HVAC fan motor squealed for the longest time but still worked. I have been a little spoiled by having a working AM/FM/CD/Cassette unit from the factory so everyone in the famile could listen to something if they wanted to.

UNTIL. . . the motor started squealing on every speed and wouldn't quiet down for anything, meaning I would have to: repair it?, replace it?, or live with it and the family would hate me for the remainder of time it took to do either of the above mentioned solutions.

Local auto parts suppliers had this fan motor with squirrel cage factory installed only, in a price ranging from $99.95 to $238.99, and with the recent layoff I opted out of solutions 2 and 3 completely, as it was GOING to be quiet, and it WASN'T going to cost me anything, much, if at all.

Back to solution 1, I had heard of a fix for this problem on another forum I belong to, NAIOA.com (North American Impala Owners Association, for the W-body Impala and all of it's good AND bad points), and after reading an old post there decided it was well within my abilities.

The panel below the glove compartment has to be removed, there are 2 quick release clips, and 1 christmas tree style push style retainer that needs a little encouragement to remove but isn't difficult.

Remove the clip holding the wire harness that runs along the left side of the blower motor (clip too) and the connector that juts out of this harness and connects to some unit on the firewall that you can hardly see, and remove the connector from the blower motor itsself, and disconnect the motor housing cooling tube too.

There are three screws holding this motor to the HVAC system air box, once these are removed (they are quite small standard size and requirea 1/4 inch ratchet and a 2 inch extension or a deepwell socket), you can finesse the motor and squirrel cage out of the air box.

This part is done. The next part is the time consuming part.

I have the luxury of having a variable power supply that allows the use of 30 amp's of power from 0 to 20 volts, and this helped me out A LOT!

I found that the housing end cap holds the bearing, and that bearing also supports the entire shaft of the motor and squirrel cage assembly along with all their combined weight, the bearing is the part that is making that awful noise, and it is NOT sealed from the factory resulting in you being able to see the end of that shaft and a small portion of the bearing.

I laid the motor and squirrel cage assembly with this opening facing up on my desk here next to the power supply, and rigged up a simple pair of wires and connectors to allow the fan to be run to be assured this was the problematic part and also to aid in lubrication.

I slowly applied enough WD-40 (any other penetrating lubricant will work too) to the shaft and bearing opening and allowed it to soak in for a while, and reapplied several dozen times in the next couple of hours, occasionally running the fan by applying 13.8 volts and quickly turning it down to a minimum, as this motor wants around 18 amps at 13.8 volts (resulting in many layers of paper blowing off from my desk), and quickly finding out that when the voltage is reduced the amperage is also drastically reduced too.

I found that this motor (out of wierd Amateur Radio operators' curiousity) will actually run off from a standard 9-volt battery too! Don't ask why I even tried because I don't really know either.

The motor needs the small area filled with lubricant (I used blue snowplow hydraulic fluid for the main lubricant but any light oil could also be used too, and after filling the little space, ran the motor, and repeated this several times over the next couple of hours until it wouldn't make any noise and was able to start the motor turning from a complete stop with only 1.5 volts and only about 2 amps, where I had to apply the full 13.8 when I began this venture.

I made sure to turn the motor assembly in EVERY direction and orientation I could while it was running to make sure the lubricant was getting everywhere it could.

When all this was done I had applied about 10 or so drops of WD-40, and probably 15-20 drops of hydraulic oil to the shaft and bearing. I have not seen any come back out and it's been back in service for a half a day now.

Re-installation of the motor and squirrel cage is just the reverse of removal, and you should be able to tell a 100% difference in the noise level, if not, I have no idea here but it worked for me.

Just in case you want to replace the motor and don't want to pay the prices in the range I listed above, and go to the local junkyard or auto recycler, here is a list of cross reference vehicles this motor fits according to all of the sources I checked.

Buick: 97-04 Century, & 97-03 Regal.
Chevrolet: 97-04 Corvette, 00-03 Monte Carlo, 00-03 Impala, & 97-03 Venture.
Oldsmobile: 1996 Cutlass Supreme, 97-00 Silhouette, & 98-02 Intrigue.
Pontiac: 97-03 Grand Priz, 97-98 Trans Sport, & 99-00 Montana.

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Old 11-23-2006, 05:35 AM
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Aw it'll be back...

With the squeal, all you did was removed all the lube from the bearing, and now it'll overheat and you'll have a blown fuse to contend with. WD-40 is a CLEANER not a lube. White grease will keep it in service for a small time but would be back to the same old squeal again. Any type of oil will attract dust and dirt from the outside into the bearing (remember going down that dirt road or being behind that dump truck with the load of dirt blowing off it?)
I've done what you described, even to regular box fans....sooner or later, you'll just have to replace it. As much work it took to remove it, it would had been better to go ahead and get a new one and not have to listen to it and wait for the fuse to blow when you need it the most (like during a COLD morning with snow on the ground) Its no fun pulling all that apart to replace it while your teeth are chattering.....and your fingers are frozen.
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Old 11-23-2006, 05:47 AM
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Evidently you missed the part "just after" the WD-40 where I filled that little cavity with hydraulic oil and ran it to let it infiltrate that space for several hours.

It has worked for others in the past, but I couldn't find the post over at NAIOA or on ImpalaHQ, if the design allows for the lubricant from the factory to stay in even with an opening on the bottom like that, I couldn't have made it worse by adding an oil based lubricant where I know unheated white grease will not enter.

Sorry, but the unemployement thing will not allow a new unit to be purchased, and the most difficult part of this changeout was the wire harness. At least it was only a noisy motor, and not the resistor pack, as that will also require this motor to be removed to get to that piece, which is what I disconnected but found out after the fact of what it was I was disconnecting.

And as far as your reference to the box fan, your are correct, as those type of cheap motors are NOT serviceable. I looked at this motor and the brushes and bearings CAN be replaced, even though it would take more work than most are capable of. You can repair a starter motor or alternator in all older vehicles by replacing a few parts and have just as good a unit as new.
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Old 11-23-2006, 08:31 AM
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Quote:
I found that this motor (out of wierd Amateur Radio operators' curiousity) will actually run off from a standard 9-volt battery too! Don't ask why I even tried because I don't really know either.
Actually that is pretty much what you're doing when your switch is set to lower fan speeds. To slow down the fan speed they lower the voltage at the motor by adding resistances in 'series' with the motor. If you do a quick search on 'series circuits' you will see that when you add resistance in a series circuit you cause 'voltage drops' across each load (or resistance). Example: if you had 10 volts through two 100 ohm resistors in series you would have a voltage drop of 5 volts across each resistor. Meaning if you put a voltmeter across each resistor it would read about 5 volts (equal drops because resistors are equal value), but across the entire circuit it would read 10 volts. If you look in the schematic I attached from a GM power goes from the fuse through the relay then through the blower motor. From there the ground side is controlled through the switch assembly. On high the blower resistor is bypassed and the motor has full voltage (red arrows). On speed 3 the current flows through the motor (one load) then through one resistor in the resistor assembly (green arrows) through the switch then to ground. On speed 2 it goes through the motor, through 2 resistors in the resistor assembly (more voltage drop= less voltage for motor), through the switch then to ground (purple arrows). Every time you lower the fan setting you are adding resistors to the circuit leaving less voltage for the motor. Unlike old systems circuits that are 'ground side' controlled are trickier to diagnose. Since there is always 12 volts to the motor a voltmeter hooked to ground and the hot side of the motor would always show 12 volts even if the switch in the dash was bad. The switch only completes the ground side of the circuit. Checking a 'ground side controlled' circuit requires different checking techniques than the old school systems which only had power when turned on but were always grounded.
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Old 11-29-2006, 11:50 PM
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8 days later and still blissfully quiet.
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Old 10-15-2008, 06:32 PM
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Another way

The trick I learned all the way back to the Vega days doesnít even require taking the motor out.
(I have used it on MoPars and FoMoCo also.)
Find the back end of the motor under the hood.
The will be a little dimple where the back end of the motor shaft is.
With a small drill, about 1/16, drill through this dimple.
Be careful not to get any chips inside the motor housing or to go too far and nick the shaft.
Clean off the chips.
Put one drop of 10W30 oil in the hole and then cover it with the thickest wheel grease you have.
You are done.
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Old 10-29-2008, 06:33 PM
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Cheap GM HVAC blower motor fix

This is one more good tip I'm filing away BUT...I need a 12 volt power supply, like to handle up to 30 amps. Buy or build? Where to buy or get a schematic with numbers for components easily purchased? Ideas please, thanks.
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Old 10-29-2008, 08:07 PM
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heres plans for one that goes up to 20 amps http://www.electronics-lab.com/proje...028/index.html
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Old 05-17-2009, 12:10 PM
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Just had to re-lubricate the motor due to squealing again, this time not as bad.

Now for the rest of the story on this motor and WHY it started squealing.

The Impala has the motor mounted upside down in the upper portion of the passenger side footwell area and has a plastic panel to hide it and all other inner workings in that area. The Impala ALSO has at the right side of the cowl area under the hood a cabin air filter, which is sort of protected from rain coming off the windshield by a press fit seal similar to a door edge seal, this is prone to coming off and will allow water to leak down into the upside down blower motor.

I have since lubing the motor the last time, removed the rubber button seal on the top of the motor housing permanently, fixed the seal on the cabin air filter portion of the cowl, and have noticed that the water that had been previously filling the pasenger footwell is no longer coming in.
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