1970 Hurst heater/AC blower fan won't go to high, help please

Northcoast300h

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I apologize if answer was already posted but I couldn't find it. When I switch to low to med, I hear a very small increase in fan speed. From medium to high, no change in speed. My fan switch remains cool and my blower motor runs without any noise or smell, however before I got it, the car was sitting in a field for 10yrs so wires and vacuum are brittle. I'm afraid to tear the dash apart.

Even on low, the air blows really hot, so no reason to fix it. However I finally fixed the AC and noticed I'll need to fix the fan speed to make the AC cool properly. Is there an easy way to fix this? Where do I get a proper resisitor and where is it located? (if you guys think that is what it is)? Thanks for any help.
 
I apologize if answer was already posted but I couldn't find it. When I switch to low to med, I hear a very small increase in fan speed. From medium to high, no change in speed. My fan switch remains cool and my blower motor runs without any noise or smell, however before I got it, the car was sitting in a field for 10yrs so wires and vacuum are brittle. I'm afraid to tear the dash apart.

Even on low, the air blows really hot, so no reason to fix it. However I finally fixed the AC and noticed I'll need to fix the fan speed to make the AC cool properly. Is there an easy way to fix this? Where do I get a proper resisitor and where is it located? (if you guys think that is what it is)? Thanks for any help.

Usually if you have a low fan speed on the high setting it is because the fan switch is defective. It is relatively easy to take the switch apart and clean the contacts but you will need to unbolt the heater control and drop it down below the dash to remove the blower switch. The switch has four little metal tabs that hold the rear of it together, unbend the tabs to disassemble the switch. A lot of the time the selector lever has disengaged the switch block and disabled the high speed setting.

Dave
 
If you have low and medium blower speeds check for power at terminal 3 on the blower resistor block. If it has no power the blower switch is bad. Blower switches can be found on EBay. If you still have problems, PM me.
 
I really appreciate the info guys. So the blower resistor block is on the blower switch as in pic below? I have the huge OEM 8 track deluxe stereo beneath the heater/ac controls, so I can't get a hand on the heater control or even see it. I'm sure I'll break a bunch of things removing the stereo. The wiring is pretty bad from previous owners splicing and overloading circuits which I fixed back to OEM, but probably didn't get all of them since I don't know much about circuitry.

Can I somehow wire a second switch from the blower or wires going to the blower and mount it under the dash to just turn blower to high? (I'd like to keep the original switch of low and medium working.) I only need the high for A/C. (I remember 5yrs ago seeing the top of the switch when I removed the upper plastic pieces to fix the dash lights. Maybe I can get to the block from there?)

Thanks!

IMG_E3545a.jpg
NOS 1960's 1970's Indak Heater Blower Motor Switch Mopar.png
 
I really appreciate the info guys. So the blower resistor block is on the blower switch as in pic below? I have the huge OEM 8 track deluxe stereo beneath the heater/ac controls, so I can't get a hand on the heater control or even see it. I'm sure I'll break a bunch of things removing the stereo. The wiring is pretty bad from previous owners splicing and overloading circuits which I fixed back to OEM, but probably didn't get all of them since I don't know much about circuitry.

Can I somehow wire a second switch from the blower or wires going to the blower and mount it under the dash to just turn blower to high? (I'd like to keep the original switch of low and medium working.) I only need the high for A/C. (I remember 5yrs ago seeing the top of the switch when I removed the upper plastic pieces to fix the dash lights. Maybe I can get to the block from there?)

Thanks!

View attachment 495377 View attachment 495378
I would recommend you ‘pay the piper’ and pull the 8 track unit, find the problem and correct it. You will learn more about the vehicle and you’ll know what you have (discovery and removal of previous cobble-jobs) in the end.
 
I really appreciate the info guys. So the blower resistor block is on the blower switch as in pic below? I have the huge OEM 8 track deluxe stereo beneath the heater/ac controls, so I can't get a hand on the heater control or even see it. I'm sure I'll break a bunch of things removing the stereo. The wiring is pretty bad from previous owners splicing and overloading circuits which I fixed back to OEM, but probably didn't get all of them since I don't know much about circuitry.

Can I somehow wire a second switch from the blower or wires going to the blower and mount it under the dash to just turn blower to high? (I'd like to keep the original switch of low and medium working.) I only need the high for A/C. (I remember 5yrs ago seeing the top of the switch when I removed the upper plastic pieces to fix the dash lights. Maybe I can get to the block from there?)

Thanks!

View attachment 495377 View attachment 495378
Pretty sure your second picture is just the switch and the blower motor resistor is located on the heater box
 
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My two cents...

If the switch was bad, the fan wouldn't work on high speed period. It can't get much simpler than that.

The blower resistor doesn't come into play on high speed, but does on low and medium, and they work, so that's not the problem.

Wiring to the fan must be good, or it wouldn't work at all.

That leaves the motor... and they are trouble prone, one of the issues being the bearings start to seize as they age and either draw too much current and/or don't run as fast as they should. I would bet that's the problem, especially after seeing so many failures with the motor or related to the motor.

It's an afternoon job... and not fun, but doable. Pull the right front wheel, then the well house. Reach into the firewall and unbolt and swap the motor.

Given the car sat for 10 years, it's not a stretch to figure on the motor being bad.
 
If you want to check the motor... It's real easy. Find the green wire on the right side of the firewall that goes over to the blower motor. Look in your FSM and you'll see it. 24-35 and 24-38 are the pages that will help you the most.

Don't have one? Download here: Resource Library – MyMopar

Disconnect and then connect a jumper wire to the battery to the motor. Bet it doesn't run any faster.
 
Well I finally tried it. Jumped a wire directly to battery and lots of air and no noise. So blower is fine. Thanjk you John for saving me time and work. So I think Davea is correct and its the switch. Anyone know the easiest way to get the switch out? If not, how do you get the switch out?
 
Well I finally tried it. Jumped a wire directly to battery and lots of air and no noise. So blower is fine. Thanjk you John for saving me time and work. So I think Davea is correct and its the switch. Anyone know the easiest way to get the switch out? If not, how do you get the switch out?

You will need to pull the heater control out of the dash, it is held in by two bolts on the back side. Once that is done, the switch can be unbolted from the unit.

Dave
 
Pull the radio out and I think you can reach the switch to remove it.

You might have to pull the whole control out, but you'll need to pull the radio for that anyway.
 
Thanks Davea!

Heater never shuts off. I just hear a "shhhh" for a few seconds when I hit OFF button but heater and blower keeps going. Heater doors are stuck at floor and a little defrost. Since blower is stuck on low, I just open the window if gets too hot inside. The few months I use the AC each year, I plug the bypass valve which means no way to put on heat. Someone replaced heater core and I think they messed stuff up. I'm thinking there's no one who restores full heater/AC units and if they did, it probably would be $2000? or more, correct? I don't think I'm smart enough to fix it myself and will probably make it worse.

Soooo, can I just connect a simple DC fan speed controller using the blower resistor wires and be done with it?
 
Thanks Davea!

Heater never shuts off. I just hear a "shhhh" for a few seconds when I hit OFF button but heater and blower keeps going. Heater doors are stuck at floor and a little defrost. Since blower is stuck on low, I just open the window if gets too hot inside. The few months I use the AC each year, I plug the bypass valve which means no way to put on heat. Someone replaced heater core and I think they messed stuff up. I'm thinking there's no one who restores full heater/AC units and if they did, it probably would be $2000? or more, correct? I don't think I'm smart enough to fix it myself and will probably make it worse.

Soooo, can I just connect a simple DC fan speed controller using the blower resistor wires and be done with it?
That sounds like the vacuum switch is the problem. You can find new ones with some searching or they can be repaired .

How To Rebuild a Vacuum Heater Control Switch
 
Thanks Davea!

Heater never shuts off. I just hear a "shhhh" for a few seconds when I hit OFF button but heater and blower keeps going. Heater doors are stuck at floor and a little defrost. Since blower is stuck on low, I just open the window if gets too hot inside. The few months I use the AC each year, I plug the bypass valve which means no way to put on heat. Someone replaced heater core and I think they messed stuff up. I'm thinking there's no one who restores full heater/AC units and if they did, it probably would be $2000? or more, correct? I don't think I'm smart enough to fix it myself and will probably make it worse.

Soooo, can I just connect a simple DC fan speed controller using the blower resistor wires and be done with it?
If the heat/AC doors are not operating, neither the heat or A/C is going to work very well. You could remove the plug from the back of the fan switch and wire it to a multi function DC fan controller, but that won't fix the other problem with the door function. You might also have a bad vacuum control in the heater control which has disabled the heat/AC door function. This was a common failure on Mopars with A/C. Probably best to pull the heater control and replace the fan switch and the vacuum switch, that should fix the worst of your units problems. If the heater core and A/C condenser are not leaking, there is probably no need to pull the air box as that is an expensive repair if you have a shop do it.

Dave
 
For better fan speed you can use the wire that goes to the pass through of the resistor for high speed as a trigger wire for a relay and run power from that relay, not through all the old wiring harness. I picked up 2 volts to the fan motor doing that.
 
I can't get my hand up there. I would need to remove the huge 8 track, (meaning I would break it). Yeah, there's just too many things wrong with the heater/AC. I'm fine with how the heater works but AC fan speed needs to be on high to make it worthy. Since I put only 500 miles per yr on this car, I'm just going to try the easiest and cheapest idea and buy a fan controller using the resistor wires. Maybe I'll be happy with that. I'll get to it once weather temp goes up, maybe in April. Thank to everyone for your help.
 
You might get to the resistor if you take the glove box liner out? I'm not with my car to look
 
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