Ac blower motor testing

[Shoooter]

How do you test a a.c. blower motor to see if it works?  It has the two wires coming off it. Just add power to the one side and ground the other? Also what is the correct colour? I've seen them silver and  black. What one is correct?

[Cuda Cody]

That would be my guess.  Not sure how much power it uses, but if you have it backwards shouldn't it just spins backwards?   

[Burdar]

Yes, one side to power and the other side to ground.  As for the color, it might depend on year.  Dave Walden's OE gold Challenger has a silver zinc plated blower motor.

[Slotts]

Before applying power, I first test the motor by spinning the shaft to see if it moves freely. If it is tight, you don't want to apply power. That could be from corrosion between the stator and armature, dry bearing, broken brush, etc. If it does move freely, try testing the green and brown wire separately to the motor housing checking if the motor has a short. If your see no reading on an analog meter or O/L on a digital, it appears the motor is not shorted.

Next, connect your + lead to the green and - to the brown, then turn the shaft. You should be reading 0 Ohms and by spinning the shaft slowly, there should be some flutter to the impedance reading by a couple of Ohms. Then I would apply power to the motor by connecting the -12 vdc lead to the brown wire and just quickly touching the +12 vdc to green and get off of it quickly. If the motor sounded somewhat quiet, without any rubbing or squeaking, then you can try it again and see how it runs. After 43+ years, they really should be serviced. Just my  (Just had to do it, Alan! ;-)

Taking a close inspection on the motor will reveal whether the motor came from the factor either in clear zinc or black paint. The usual dead giveaway is looking at the motor shaft side end cap. Lots were zinc plated and painted black later on while on the firewall to clean them up, if you will.

I do restore the non a/c and a/c motors if you run into any issues.







Jim

[1 Wild R/T]

Hooking up power should cause it to run but that only tells you it will run, it doesn't tell you much about the condition of the motor.... If you have a multimeter with an Amps function hook the meter up in series with the motor & see how many amps the motor draws... A good motor will draw less than 2 amps.... But I've seen them draw 8 amps & still run fine.... I've seen fresh "remanufactured" motors that draw 4-5 amps...  Blower motors are one of the bigger loads passing through the bulkhead which is why blower speed switches & the connectors were/are commonly burned.... And why it's another place where relays are a huge plus.. If it's an A/C car typically even on high you barely get any air movement... But add a high relay & suddenly it's almost like a modern car....

[Slotts]

That would be my guess.  Not sure how much power it uses, but if you have it backwards shouldn't it just spins backwards?   

Cody and to All,

The draw on these motors averages about three amps while running full speed.

Here is a very done animated graphic imaging link to show how a DC motor can be reversed. For the three speed wiper motors, this is what the variable or three fixed speed wiper switch is doing inside to get the motor to park. The two speed motors are designed a little differently and am not going into all of that... 

https://www.wisc-online.com/learn/career-clusters/stem/iau9708/reversing-the-rotation-of-dc-motors Page 3 of 7 allows you to reverse the motor rotation.

Jim

[Cuda Cody]

   Wow guys, I learned something new!!!!  And that I'll just send my motors to be restored when I need them done.  Might need to send a batch to you @Slotts   

[1 Wild R/T]

  Wow guys, I learned something new!!!!  And that I'll just send my motors to be restored when I need them done.  Might need to send a batch to you @Slotts   

Sending Jim a batch is probably the best option... I have a box that I need to properly package & send to him too.....  Beautiful work....

[Shoooter]

Mine looks to be zinc coded then painted black. The zinc would look better as my firewall is black

[Shoooter]

Tested the motor and it works perfect