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Blower Motor Relay

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farna View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2018 at 7:00am
The e-bay waterproof PWM DC controller looks great, but they are 3.5"x2.5", and 2.5" thick. I suppose you could hide two under the dash though. Screw to dash on passenger side between switch and where the wires exit the body. No one will know but the installer. 10-60V should just be the input range, not the voltage setting range (needs at least 10V to operate). So while it may be a better solution than a resistor, it will take up more room. But it shouldn't get very hot.

The neat thing is you adjust to whatever speed you want low and medium to be. I used a universal blower motor rheostat type controller for low speed when I replaced a two speed (three wire) motor with a universal single speed one. That thing got hot and was mounted under the hood, but I set it at whatever I wanted low to be. Two of those could be used.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2018 at 8:03am
Farna, well I did not think of a water proof version, but that can be an option if expecting to replace the relay and resistor pack assemblies on the firewall or placing on the evap box.

Depending on circuitry, some smaller versions are probably MOSFET switched, which do not heat up like power transistor switches, so heat sinks can be slim line or even the aluminum housing.

Rule of thumb, get a module that has at least a 5 amp rating higher than the motor current rating. Even though the continuous current may be 15A, the instant on current can be much higher. Some PWC modules don't have a current limiter on duty cycles above 90%, being 100% duty cycle is continuous current. So if using one that just fits the current rating, may end up failing early when starting the fan in high range, rather than soft starting, at low and working up the range.

Most are small enough to fit under the dash, just the switch to control them may need some changes to the stock fit of your car's instrumentation.

To make an old switch work with a rheostat adjusted module, you can wire in resistors at each switch position above off, to be the resistance given by the removed rheostat. This a clean stock look and feel. The only difference is the over all function is now a modernized and efficient device.

To obtain proper resistor values, just play with the rheostat for required fan speeds needed, and measure the resistance. I would imagine rounding up or down to the closest value obtainable in a 1/4 watt resistor will work for using your factory switch to control the fan speeds.

If one wants to get elaborate, they can make a pigtail to connect to their factory switch, to keep the factory wiring intact, while disconnecting the factory fan circuit and tying it up out of the way.

71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeeperJolene Quote  Post ReplyReply Direct Link To This Post Posted: Sep/25/2018 at 10:43pm
Well, the blower fan is definitely being blocked by something, which would explain why it smoked when the previous owner tried to use it.My guess is some sort of nest or dead animal.

Does anyone know the resistor values of the Jav switches? I was hoping to get the new wire harness built before taking the dashboard apart, but it seems like I won't have a choice. It's not a huge deal since I'm pulling the engine and transmission out of it currently and it's not going anywhere for the rest of the winter.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Sep/25/2018 at 11:28pm
Have you ever considered that the motor ITSELF may be shot, rusty, stuck, etc.?
It's very unlikely a "dead animal" is "blocking it". There's a lot of space around that cage. Something may have nested, but in my experience over the years, it's typically the motor itself that's the problem.
They are so simple to pull and look at in most AMCs (unlike CHEVROLET where you remove - or CUT, the inner fender for access)
The blower resistors run HOT - and are typically cooled by the blower itself, or by being on the firewall in a perforated metal shell for air movement, etc. They are wire-wound open air types in many AMCs. You know they run HOT when the connections are typically rusted and corroded and the plastic shell over the main wire is often melted or otherwise deformed. Most blower resistor issues aren't the resistor, but are the connections at or to the resistor. If kept cool, the resistors THEMSELVES don't usually fail. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeeperJolene Quote  Post ReplyReply Direct Link To This Post Posted: Sep/25/2018 at 11:37pm
I say this because it does start to turn and something is preventing it from continuing to move. I've been through this before with my Camaro, my old Ford and a friend's Chevelle. When they sit unattended and exposed for as long as my Jav did, especially when leaves and such fall out when I bump the air box, there's a good shot of a nest inside.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote S Curry Quote  Post ReplyReply Direct Link To This Post Posted: Sep/26/2018 at 9:18am
I don't know how long mine had been sitting, the tires were date coded in 94 and were brand new. This what I found on the heater core. Same in the fan box, don't have a pic. Fan was stuck also. Just took a disassemble clean and lube and good as new.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeeperJolene Quote  Post ReplyReply Direct Link To This Post Posted: Oct/04/2018 at 6:31pm




Yeah, it was definitely a nest. The motor works just fine now that it isn't blocked up.



Edited by JeeperJolene - Oct/04/2018 at 6:34pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Oct/04/2018 at 11:13pm
At least the motors on AMCs are simple to access and replace, and in most cases, save for EAGLE, the housings aren't that bad, either.
Eagles really suck when it comes to HVAC.

While finding the cause to be that is satisfying and is cheaper than a motor repair, it should be pointed out for the lurker that this is actually not a usual situation.
It happens, but isn't the first thing to suspect (but it's so very easy to check for!)
In 45 years of repair on hundreds of automotive HVAC systems (in shops where I have worked - all brands from AMC to VW to Lexus) and having rebuilt or restored dozens of blower motors, the "nest" situation isn't as common as one may think.
In fact, in 45 years doing this, I have never seen a nest that big and bad. I've never seen one that actually stopped a blower motor for that matter! 
So no, that would never be my "first guess". Every single one I've dealt with as a tech over the decades has been related to the physical or electrical aspects of the car's systems, the motor, etc.
And on Chevrolet, ugh, those were the pits.

I have three cars in my shop that have sat outside for years, decades even - each one in different circumstances, but outside.
One was in a grassy lot in Rural CA, another in a sort of remote part of MN, down in a low area near fields and woods, another was "god only knows" but the bottom indicates it sat in dirt for many years (the springs were rusted beyond holding the car up), and there's another outside of my shop which is 50 feet from a rural wooded area to the south, with a creek near, and not far from a river, and on the other side, bean and corn fields, walnut trees and so on.
No "nests" in any of them. 
In two cases the blower motor was stiff from sitting, there was nature's debris in the housing (leaves and stuff that got through the cowl screening and other holes), in another it was actually clean in the housing and the blower motor was stuck - but after five minutes was working fine with a little work and lube. The fourth, sitting outside among the mice, chipmunks and other "rodents" actually spins fine.

Even all of the blower motors on my shelves are situations where the motor itself was the issue, not nests.

That indeed is not common, and not something I'd expect to find, especially to that extent. 
By the way, forget dryer sheets - the Iowa mice, and I am NOT joking, drag them together and use them for NESTING MATERIALS. Yup, I've found nests made of the dryer sheets I've used to keep mice away from things. 

Maybe Iowa rodents are more discriminating!

But you'd think that doing this since the early 1970s I would have found at least one that was as bad as that.

Now if you want to talk COMBINES - fire one of those up in late summer to get it ready and STAND BACK and rats, parts of rats, mice and more come flying out the back as if thrown by a Cardinals pitcher. You DO find nests in those - but then there's FOOD around. Typically rodents build nests where they can cache food easily, it's not far away and there's a bit of shelter or warmth involved.
(it's one reason I try hard to avoid FOOD in the car - no one will be eating their McDonalds in my cars. it attracts things like pictured above!)

Gotta stop for some sleep - have to get up and drive an hour/55 miles in the AM to see an attorney, deal with insurance, wrongful death claims, and more......... there goes another full day!
This week was a total bust - dentist today, saw dentist on Tuesday, said to come back today, power was out over 11 hours Wednesday so no shop work (no lights, NO INTERNET, no tools) and had to get the plating tanks back up to temp. what a wasted week. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jul/09/2019 at 7:15am
The resistance isn't that critical. Just get a resistor pack from another car, even a GM. You won't notice if the fan blows slightly different than stock on low and medium speeds. I put a relay in the high speed line (direct from battery) on mine, but it didn't really make a difference. I run the fan on high a lot, so maybe the fan switch will appreciate it!
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jul/09/2019 at 7:56am
Never mind frank - he's a SPAMMER.
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