Heater fan blows all the time

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Oldspowered

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As soon as I turn the key in my '75 Duster the blower motor is running on high. The fan switch doesn't affect it, and sliding the climate control to "off" does nothing. All the other function of the climate control work (temp, vent settings, etc). I looked at the back of the blower motor and tried to trace the wires to just unplug it but I never found a disconnect point. I tried to pull the climate controls out of the dash but they only come out a little way before being stuck. I don't want to pry on the bezel any harder out of fear of breaking it.

I searched but didn't find anything like my problem.

This is my first Mopar, so I am making sure I'm not missing some obvious answer. Worst case scenario I'll re-wire it like I do my other old cars.
 
maybe its the resistor the one when you look under the glovebox with the two screws. that usually holds the fan on high when bad, could be the fan switch.
 
Oldspowered,

I'm not sure if your heater set up is the same as the mid 60's cars, but if so, here is a link for a heater box rebuild that will help you get the box down so that you can look at the fan and its connections:

http://www.moparmusclemagazine.com/...aliant_heater_box_assembly/box_reinstall.html

Since your fan runs constantly at high speed, it sounds like the resistor is either damaged or bypassed. Depending upon your set up, you should see the heater motor speed resistor mounted on the heater box. If you look closely in Part 15 of the article, you can see the fan motor resistor to the right of the heater core and below the fan (the resistor is a coiled spring inside the box, and the 3 prongs for the connector stick up from the box).

Hope this helps.

heater core photo.jpg
 
Your fan switch doesn't go to off like earlier models. The selecter ( upper slider ) all the way left should turn the fan off. The resistor pack is mounted in the air box under the dash. Those are in the ground side of the circuit and create the lesser speeds. If every resistor was burned open you would still get high and off.
I would say you problem is in the climate controller but I've been wrong before. Hope some of this helps.
 
Just wanted to share that I fixed this little gremlin problem.

Whoever worked on my car before apparently swapped out the blower motor. There were two choices for the power wire that he hooked up, and he chose the wrong one. There are two similar connectors on the passenger side firewall that the blower motor will power wire will plug into. If he had paid attention he would have noticed that the blower wire is green. He had plugged it into some blue wire (paired with a round connector tan wire) that I have no idea what it goes to. I saw an unused green square connector sitting in the firewall wiring loom and lo it plugged into the blower motor. Now I have three fan speeds instead of just W.F.O.

For some reason whatever power wire the blower had been plugged into supplied key-on power, so I guess the previous owner just lived with it.
 
Now to figure out why it keeps popping the #4 20-amp fuse. I might have fixed this problem by straightening out the blower wiring, but I popped my last 20-amp fuse today and need to buy more.
 
If the burners are strong when it fires up, it seems that if the gas pressure is not set correctly at the entrance and exit for a lot of gas. Call your local gas company and tell them you think you smell gas. This will be the roll. It takes a special gauge to adjust pressure and do them after soap for leaks. This is the problem for a lot of gas will cause it to be very strong.You need to get them out anyway high pressure can be dangerous.
 
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