Heater blower motor wiring

[soundcontrol]

My heater fan does not work, it's not even hooked up (that's probably why it dosent work  ) Now, trying to figure out how it is hooked up, it's an AC car, looking at the schematics the motor is labeled "Air Conditioning motor" in the wiring for the engine compartment. In the instrument wiring it's called "Heater Blower motor".. (if I'm looking at the right thing here.) In the engine compartment I think it should be connected to point B on the bulkhead connector with a dark green wire. In the instrument wiring diagram though, I follow the heater blower motor wire from the fusebox, to the blower switch, then it goes with 2 wires to a resistor, thru that to some vacuum switches for the AC that I do not know the function of. All my AC stuff is disconnected and does not work. I would like to just get my fan motor working so I can get fog of the windshield on a rainy day. I will later install my Vintage AIr AC that I bought.  I can not find how the fan motor connects from the engine compartment thru the bulkhead to the fan switch in the schematics.

[pimp2303]

I will be following this, I have not even looked at my AC wiring yet. Its all hooked up under the hood as far as compressor and lines going to the heater core and etc. but not electrically.

[ShelbyDogg]

Look for an old post for A/C blower motor wiring.  I helped out a guy a few years back and posted a blower motor wiring diagram in his thread.


Found it here:

http://www.cuda-challenger.com/cc/index.php?topic=65095.0

[soundcontrol]

Got the fan to work briefly today. Found the dark green wire from the bulkhead connector, loose, tied to one of the transmission oil cooler lines under the car 
tested it and the fan works on hi and AC Max, not on defrost (the mode I want). After running for a while it slows down and stops. I guess this is controlled by a bunch of vacuum switches that dosen't work? Never had an AC car before so I have not disassembled one. And what is this? Hanging loose under my ashtray...

[soundcontrol]

Look for an old post for A/C blower motor wiring.  I helped out a guy a few years back and posted a blower motor wiring diagram in his thread.


Found it here:

http://www.cuda-challenger.com/cc/index.php?topic=65095.0

Great! Thanks, gonna read thru that now. Wiring looks easy. What acually controls the air going to the defroster? I guess vacuum....




yep, just read it, my vacuum lines are long gone, guess I have to start checking the switch and see if I can figure out the vacuum problem.

[JayBee]

That box is the crossover network used with 3 speaker ( & 5 speaker ?) stereo systems. It's suppose to be mounted on the left side of the glove box.

[ShelbyDogg]

If you fan only works when the switch is on A/C and HI, you'll see by the diagram that you don't have any of the resistor circuits connected to run the lower speeds. Look for a hanging plug that plugs into a matching connector right in the middle of the heater box, facing the passenger seat.  The squiggly lines in my diagram are actually the coiled up resistance wires on the back of the board.

[soundcontrol]

Found one of many problems, the fan motor is bad, it works on AC Max and hi speed first, after a while it stops, I hooked up a meter and the voltage drops to 6 volts even on AC high, the wire gets very hot, then it stops. Even if I run the fan direct on the battery, it gets hot and stops after a minute or so, it also makes a noise thats not normal. I measured voltage on all modes, and the switches seems to work, I get voltage on all, (and the plug on the heater box is connected) it just not enough to get the fan going.
Oh well, I just wont drive in the rain this summer....
Is the fan motor easy to change? (maybe I can borrow one for now), or do I have to remove the whole heater box...


JayBee, thanks, interesting, so the small corner speakers were not fullrange.I didn't know the stereos were that fancy at the time!

[ShelbyDogg]

Blower motor comes off from the engine side, very easy to change. Try greasing the ends before replacing it.

[roadman5312]

  When you get the blower motor fixed the vacuum motors will need to work correctly to switch the air from floor to dash vents to defrost vents. You could also wire tie (for now) the vacuum motor that controls the defrost door open. Just thinkin out loud. Hope it helps.

[soundcontrol]

I'll try to remove the fan motor, open it and see whats up.


I only need defroster so if it is possible to lock the vacuum in that position I will do it.
I don't know how the vacuumsystem works, but there is nothing hooked up to the intake now, found a loose hose hanging
behind the heater box, maybe thats the one going to the intake...

[soundcontrol]

I removed the motor, it felt like it did not move very freely, had a resistance to it. Took it apart, looks fine inside, I measured the windings on the rotor and stator, see no problem there, I cleaned the contact area for the brushes, and greased the end bearings. Brushes looks fine. Now, when I put it together it moves fine I think, but as soon as I tighten the bolts it gets stuck again...and the bolts need to be tighten to a certain point to make the whole casing solid, hmm. Don't really know whats up with this.

[ShelbyDogg]

I removed the motor, it felt like it did not move very freely, had a resistance to it. Took it apart, looks fine inside, I measured the windings on the rotor and stator, see no problem there, I cleaned the contact area for the brushes, and greased the end bearings. Brushes looks fine. Now, when I put it together it moves fine I think, but as soon as I tighten the bolts it gets stuck again...and the bolts need to be tighten to a certain point to make the whole casing solid, hmm. Don't really know whats up with this.

Anyway to have the mounting bolts clocked wrong? 180 degrees off?  If you cant fix it, Rockauto.com has them new for $38.99.

$36.99 new at Autozone.

[soundcontrol]

Anyway to have the mounting bolts clocked wrong? 180 degrees off?  If you cant fix it, Rockauto.com has them new for $38.99.

$36.99 new at Autozone.

Don't think so, there is holes in the stator core for the bolts, and the bottom part (facing th eengine compartment), has the cables attched so I cant turn that one 180, maybe the other part of the casing could turn 180, but it looks very symmetrical, I will try turning it though.


Looking on Rockauto's website, can't find it there, is it named "Blower Motor"? They don't seem to have a search function on the site. I looked in the parts listing for 70 Dodge Challenger.

[ShelbyDogg]

Check rockauto under DODGE, 1972, Challenger, 5.2. Heating and Air, blower motor.

I don't know the difference between a 70-71 blower motor and a 72-74 one, but the outside will be the same.