1960s ‘59-‘62 blower motors

[David Greenburg]

I thought I'd share a bit of info I picked up today from an extremely knowledgeable local mechanic who works only on pre-'79 American iron. He informed me that th '59-'62 cars use different blower motors depending on whether the car was air conditioned. For some reason, the motors in non-a/c cars rotate clockwise, while a/c cars rotate counterclockwise. He's seen a number of instances where owners bring him cars that have had their blowers replaced, and then claim the new one is not very powerful, only to find that the blower was replaced with the wrong one. So keep that in mind if you find yourself shopping for a blower motor.

[Moody]

Thanks David,
That's good to know!

[TJ Hopland]

Do or did the fan blades typically come with a replacement motor?   Either way a different direction isn't going to be the most efficient.

[Cadillac Jack 82]

Good to know!  I'm planning on servicing my heater box in the fall.

[JayRudig390]

This makes no sense

[59-in-pieces]

James,

Not that I disagree.

But, please elaborate - explain.

Have fun,
Steve B.

[Gabe Davis]

Can't you just reverse the polarity of a DC motor to have it match the direction that the fan is optimized for? So if the motor is spinning the opposite direction that is desired just pull the pins from the connector and swap them.

[David Greenburg]

I don't have first-hand experience with this issue; it was mentioned to me in the context of "I'll bet you didn't know this" in course of discussing some a/c issues.  But he did not think it made sense, either.  He thought perhaps it had something to do with the ducting. But I have the utmost faith in this guy and his knowledge, as do a number of other members who are not on the forum. He only works on pre-'79 US cars, and has pretty much seen it all.

[59-in-pieces]

I'm no expert. but the blower motor has a squirrel cage fan inside the assembly.
There are fins on the fan that when spinning cause air flow.
If you simply reversed the wires, assuming that changes the direction of the fan, wouldn't the fins spin backwards, and not push air

Maybe the fan would then suck air out of the passenger compartment.
That would be nice while you cruise along in your Cadillac smoking your cigar, and the fan sucks the smoke out - LOL.
Wait, there is an easier way to clear the cabin, roll down a rear window, yep.

Have fun,
Steve B.

[TJ Hopland]

It depends on the type of motor if just reversing the polarity will reverse the motor.  If its a permanent magnet type then yes its that easy but that isn't the most common design.  Most designs both the rotor/armature/turning part and the field/housing/non turning part are electro magnets.

Its the relationship between the spinning and fixed parts that set the direction so in the case of a permanent magnet that part can't change so flipping the electric part changes that relationship so the direction changes.   With both being electro you have to flip one section.  If its a motor that is intended to be reversed the wires for both sections will be brought out so this can easily be done. If its not intended to be reversed the wiring will be internal so flipping the input won't change that relationship and the rotation won't change.

An example of this is starters.  When you change a car from POS to NEG ground the starter doesn't spin backwards.  On starters the connection between the armature and field is internal.


A regular propeller style fan blade will flow in different directions if you reverse the rotation.  Depending on the exact design it may not be as efficient reversed but they will still flow decent reversed.  The 'squirrel cage' fans don't work like that.  If you spin them in the wrong direction the flow stays in the same direction but you loose like 75% of the efficiency and with some designs end up overloading the motor at the same time. 

My guess why Cadillac would have had different directions likely had to do with the way the duct work laid out and possibly the back pressure.  Adding more ducts and restrictions for the AC system may have required a different blade design to deal with the pressure.  Some blade deigns only work with very low restrictions while others only work with restrictions.     

[Cadman-iac]

Can't you just reverse the polarity of a DC motor to have it match the direction that the fan is optimized for? So if the motor is spinning the opposite direction that is desired just pull the pins from the connector and swap them.

  If the motor has 2 wires coming out of it, then yes, the polarity can be reversed, but it also depends on how the motor is wired internally.
 If the motor housing is not connected to the internal wiring, meaning that it's insulated, then it's really easy to reverse the direction by reversing the polarity. (All of the Japanese cars use this type of motor, I think it's referred to as an insulated ground circuit, which requires a separate wire for the ground circuit. American cars used to all use the  chassis as the ground circuit.)
 But most motors usually use just one wire at a time and the housing is grounded, one wire makes it rotate clockwise, the other counterclockwise, and the switch determines which one.
The field windings, (usually just 2) are each wound in opposite directions which is what sets the magnetic field that turns the armature. One winding is for counterclockwise, and the other is for clockwise, like a window motor.
Either way, only one wire is powered at a time, and the housing is the grounding point.

On a single-wire motor, you cannot "just" reverse the polarity to make it turn the opposite direction, because the circuit uses the motor housing as the ground path.
 To reverse this type it would be extremely difficult, you would have to insulate the motor housing and use a second wire connection on the housing as the ground and/or the power source, and the original supply wire would have to be connected to a switch along with the new wire, and the switch would have to do dual duty, one side would supply power while the other side is connected to ground. It would have to simultaneously switch the power and the ground from side to side in order to change the rotation.
 Vehicles from the 80's up used this type of switch and motor on the windows. I found that out while modifying my 88 Suburban to use a Cadillac window motor from the 50's, 60's.
 I had to modify the switch as well to eliminate the alternating grounding circuit to work with the older design motor. It's not difficult to do, but you have to know how.
 But to answer your question quickly, NO, it's not really a good idea.

 Rick
 

[Brett Baird]

I have run into this issue.  Indeed there are two different blower motors available for '59-'62. One rotates CW, the other CCW. Otherwise they are physically identical.  The motors are case grounded - meaning that a single wire provides voltage to the motor and the motor housing provides the ground.  For that reason, as Richard points out, it is not possible to reverse the polarity. If my memory serves me correctly, the AC blowers rotate CCW When looking at the shaft/fan, and are difficult to find new.  The motors that rotate CW are easy to find - even Rock Auto has them.

[Clewisiii]

I can confirm that the fan blades are angled in opposite directions between my original AC car blower motor. And a replacement motor I bought several years ago.

I never really looked at these side by side. They are very different.

[TJ Hopland]

Are those two supposedly interchangeable?   The right one looks like the 70's 80's style.   

[bcroe]

Basically a DC brush motor can be reversed if you
switch the 2 wires going to the brushes (leaving the
field the same).  The problem is getting it apart. 

A permanent magnet motor could be reversed if you
have facility to remagnetize it, otherwise brush
wires must be reversed.  Since the neg is generally
connected to the case, reversing the external wires
works but will give you a hot case.  Bruce Roe

[Cadman-iac]

Basically a DC brush motor can be reversed if you
switch the 2 wires going to the brushes (leaving the
field the same).  The problem is getting it apart. 

A permanent magnet motor could be reversed if you
have facility to remagnetize it, otherwise brush
wires must be reversed.  Since the neg is generally
connected to the case, reversing the external wires
works but will give you a hot case.  Bruce Roe

Bruce,

Not sure I follow your wire swap. Correct me if I'm wrong, but doesn't the power path on a single-wire motor flow from the input wire, around the field windings, then to the positive brush, through the armature to the negative brush, then to ground at the housing/case?
Just swapping the two brush connections wouldn't have any effect on it that I can see.

Rick

[TJ Hopland]

You kinda have to know what sort of motor you are dealing with... permanent magnet, series wound, shunt wound, compound wound, commutative series wound?  You can build a motor to be easy to reverse or almost impossible to reverse. 

[bcroe]

Bruce,
Not sure I follow your wire swap. Correct me if I'm wrong, but doesn't the power path on a single-wire motor flow from the input wire, around the field windings, then to the positive brush, through the armature to the negative brush, then to ground at the housing/case?
Just swapping the two brush connections wouldn't have any effect on it that I can see. Rick

Rick, reversing the pair of wires to the brushes will
reverse the magnetic field in the armature, without
affecting the field (permanent, wound, series, parallel,
or compound).  That is how a brush motor is reversed,
actually doing it could be a bit of a mechanical
challenge.  4 poles/brushes you move 4 wires 90 degrees. 
Bruce Roe

[Cadman-iac]

Bruce, TJ,

Thanks for the input, I didn't think anything other than the typical 2 brush motor was used for a blower motor. That's what I was basing my comments on.
I know I mentioned the 80's design window motors, which are a permanent magnet type, (I refer to them as a pancake motor because of how they look,  and are an insulated ground motor making it easy to reverse), the typical 2 wire 2 brush window motor, ( and antenna motors), from the 50's to the mid 70's used 2 field windings that were wound in opposite directions, and only one was used at a time with one or the other wire as input.
The only 4 brush motors I've ran into are starters and winch motors. The winch motors use solenoids to reverse the polarity to change the rotation direction.
But my knowledge is limited to just what I've I've learned from rebuilding what I have out of necessity.
I defer to your knowledge/experience/opinion on what it takes to do the aforementioned task.

  Rick

[Cadman-iac]

  On a side note here,  the typical old-school 2 wire window motor, in my opinion, is not as powerful as the size makes it appear because it can only use one field winding at a time, whereas the later "pancake" 2-wire permanent magnet motor is half as large but just as powerful, making them fairly equal. The advantage of weight savings goes to the newer design, but in my opinion it sacrifices dependability and longevity.
 The permanent magnet motor also has a built in circuit breaker for protection, but it can't handle a lot of current. The older motors don't have a breaker, they rely on the fuse in the circuit for protection.
That's something I learned from using the 56 window motors in my 88 Suburban. I expected much powerful operation from the swap, but they operate  just the same.
The difference is in how long the older motors last.
Now I have a theory that the older motors will perform better if the switch and wiring were upgraded to a heavier gauge.
Unfortunately I had to use the original master switch in the Suburban in order to be able to still operate the rear windows from the drivers door. I only converted the front doors since they are used so much more.
So the master switch is an odd unit now, the 2 front ones now just switch 12v positive from one wire to the other for up or down.
However the 2 rear switches reverse polarity to the motors for up and down as designed.
To accomplish this I had to eliminate the ground circuit for the 2 front windows, otherwise it would simply short out the first time I used it.
I thought I'd throw this out there in case anyone ever decided to try it.
The older motors mount to the newer regulators exactly the same. If memory serves, I think I had to swap the bushing for the drive gear on the regulator so the gear shaft would fit. It's been 5 or 6 years since I did this, so I'm not positive now.

Another concern if you are swapping to the older, bigger motor is clearance issues.
I found out that the bigger motors, (I used the round ones instead of the rectangular type), just barely fit inside the door. There's maybe a 1/16" now between the motor and the door skin, whereas the pancake motor had at least an inch.
The upside to this swap is that I have not needed to replace any more motors.

Rick