Technical Whats the trick with old heater fans that blow the wrong direction ?

Hello,

When we worked on those small electric motors and rewound our own wires, it was simplicity, but one little mistake causes odd ball firing or misfiring. So, your question had many good answers and since nothing seems to work, perhaps it is the new motor that has their wire connections crossed.

At those assembly factories, not all is done with robots and sometimes, on a Friday or Monday, we all know the stories about wanting to go home or not wanting to come back from a rousing weekend.

So, checking inside of your new motor housing to see the connections are in correct order, might give you a different look at the problem. It was usually just changing the wires, but sometimes not all answers work for all problems.

Jnaki

If worse comes to worse, just take the new motor back and get another one. Have the parts guy attach the wires from the motor to the house battery and see if it turns correctly. If one does not work, get another one in exchange.

 

G'day Jnaki, The silver motor and fan is the same grungy one in the first pic. Came out good did,nt it. Spins like a top now only the wrong way . All my own work

 

There's a big difference between series wound and permanent magnet motors. Permanent magnet will run backwards with reversed polarity input. Series wound will not.

And I'll add a little bonus information. A series wound motor will run on AC or DC. Take your 110 volt circular saw or electric drill off the shelf and connect the two square prongs of the electrical plug to a 12 volt battery, then pull the trigger. It'll run, but slowly. Now reverse the two wires at the plug. HOLY CRAP, it still runs the same direction.

You need to go from this:



To this:

 

And there is your answer.

 

AC does does not have polarity like DC...

 

Ah, but it does... but it alternates!

 

ground and hot crossed. Just switch 'em and call it good.

 

Does it have a switch like this?

 

Nope. He said he tried that in his original post. You're not the only one who didn't see that.

 

Nope missed that completely.

makes zero sense the motor is DC and reversing the wires should reverse the direction that it spins. Unless of course it grounds though the chassis and the two wires are both hots. I suppose that is entilery possible. Hmmmmnnnnnnnnn gots me on the ropes at least for the time being.

 

Could it be from a negative ground or later model vehicle and the two leads are speeds - high and low? With the motor itself being grounded by its mounting?

 

yes it could indeed. That being the case it may need to be opened back up to see if there is a different way to run the wires or perhaps it needs to be polarized as is done with a voltage regulator or perhaps the fan blade can be reversed. I had to reverse the fan blade on an old Stude blower motor I used in a later model Willys a few years back.

So many solutions

 

See post #33.....

 

My old heater came with a reversible 6 volt motor. If you can get one of these original switches which can still be found with a little searching, you should be able to make the heater work as intended otherwise just reversing the wires should do the trick and just run it.



My heater used the reverse function for defrost but works fine with the fan pushing the air through the heater core.



This what the brushes looked like. we eventually abandoned the reversible motor due to noisy un-repalcable bearings and went with a 12 volt motor from NAPA. There are several available.

 

No, tried that. At the moment i,m putting some vintage Marchal headlights together. Still have the whole year ( 3 days year sure went fast ) to get this heater in shape.

 

No polarity unless it's like building wiring with a grounded neutral...

 

New power source for fan. Not 12 or 6 volt and reversible.

 

It still has polarity. The neutral is only there if it's a dual-voltage system such as 120/240 or 277/480. No neutral needed in a single-voltage system. Without polarity, electricity won't flow in either a DC or AC type system.

 

Steve, you win, lol....

 

DC motors with permanent magnet fields will change direction by simply reversing the wires. You find these in window motors starting in the late 60's. However, if it has a wound field it doesn't work that way. Most DC motors built prior to the mid to late 60's have wire wound fields.

 

Think about changing an old Ford from 6 volt positive ground to 12 volt negative ground. Most leave the 6 volt starter motor and by golly it still turns the engine in the correct direction.