Does anyone know what this part does? It bolts right between the firewall and heater blower fan. It hast three coils like heater elements. Two of them on mine are broken. But I don't know what it is for. Any ideas??

 

--GoatBoy--

sounds like that might be the resistor pack for the heater fan speed control.......

 

way back when, those coils of resistor wire were exposed.

 

 

just a guess however

This is the fan speed regulator if I'm not mistaken. It's what is responsible for the different speeds for your blower motor. They are very often burnt out like yours.

 

GD

I am 100% positive that that is the heater blower motor resistor. As you begin to lose speeds (say like 1 and 2 dont work... its because of that little guy)

 

You may want to grab a handful of them from the junkyard as sometimes they like to break if you just look at them funny.

 

I have replaced 2-3 in my day and had mixed luck. My 87 I got a perfect one. For my 87 turbowagon I think I got one that had all but 1 speed working. My 88 had a speed or 2 out, but I never got around to changing it.

Yup. That is the resistor pack for the blower motor.. I keep a spare for just such an emergency

THANK YOU!! Temporarily I have wired a toggle to the blower fan but now that I know that is the part responsible I can fix it up right! Thanks to all!.

 

--GoatBoy--

Yep, I currently only have full speed on mine becuase of that.

I should replace that little sucker. My heater doesn't have 1 or 2.

I need to get around to changin mine as well. Once I start my 87RX I must wait for about ten -to- fifteen minutes before the blower will up and come on. Only takes about five for the car to warm up but I must wait for 10 to 15 mins. Even then when it comes on speeds 2 through 4 work fine but the lowest setting(1) is off.

Yeah, my 89 DL only has 3 and 4... but at least she's always warm!

 

I never quite finished figuring out a way to convert those fragile little things to those from a another make, namely chevy...those ones never go.

 

Of course, If we knew wht the actual resistance values on a NEW resistorpack was, maybe standard resistors would work.

Mine went out all together. Originally it was just 1 and 2 that didn't work. But then all of them went out. I tapped a hot wire and tapped the line to the fan and threw a toggle switch into the mix. The weird thing is that the switch flipped on still allows me to adjust the spped through the regular fan speed selector. So I flip the toggle on and then can adjust the fan speed by the regualr switch. But only 3 and 4 still work. Just like before. This wasn't intended. So I am not sure how I managed that. But I eventually would like for it to work normally again.

 

--GoatBoy--

There are four fan speeds, and three resistors.

 

The reason the blower resistor pack is in the airstream of the actual blower fan is to keep them <the resistors> cool, and holding back <resisting> that much current creates a LOT of heat.

 

Now here's the catch. THe LOWEST fan speed requires the MOST resistance. The more resistance, the less amperage flow, and the slower the blower spins. The higher resistance coils also tend to be physically smaller. <like a tiny staw can only pass so much milkshake>

Therefore, when the blower is on its lowest setting, it is also moving the least amount of air, when that poor little resistor is creating the most heat, and soon, the resistor just bites the dust...

Thats why 1 and 2 so commonly go, because number three is resisting the least current, and the blower is moving enough air to keep that sucker cool <and the rest of the car warm >

 

Number 4 is straight-though, so to speak, it bypasses the resistors.

 

Your switch setup is probably giving a resistance similar or close to what number three might have been... ?

 

I'm gonna go figure out a way to replace those freakin things...sounds like we ALL need a solution.

where is this resistor pack on a 1980 ea81?

I'm gonna go figure out a way to replace those freakin things...sounds like we ALL need a solution.

 

 

 

 

 

Here it is, with hard wiring to the FET + heatsink in the airstream this will give you proportional fan speed control. Just mount the fan speed switch on the PWM controlling Pot. You get continuously adjustable fan speed from slowest to max.

 

 

http://electronickits.com/kit/complete/motor/ck1400.htm

I fixed my blower resistors (1 & 2 were out) by removing the ceramic like glue stuff that suppose to stabilize them and twisting the broken wires back together, a temporary fix at best but seems to be working for now. If you do it try to preserve as much wire length as possible so the resistance doesn’t change to much and make sure none of the coils are touching each other when your done.

 

A better solution would be to measure the resistance of a good set and replace the coils with the proper value wire wound power resistors, measuring the current draw would also be a good idea so you could select resistors with the proper wattage capacity.

 

Subarubrat, the motor controller is a good idea but the 5 amp max rating of the one you found seem a bit low. I’d check the current draw of the blower at full voltage first, or just use the fuse rating for the blower circuit as a guide (I don’t recall it right now). I’d guess the blower is going to draw around 15 to 20 amps and you may find that motor controllers in the power range are a bit more expensive.

 

Gary

The 5 AMP limit is due to the thin nature of the traces on the PCB. As I said, runing a hardwire to the FET would fix that problem. The actual FET is rated at 50 AMPS and that is a fairly low grade FET. There are solder in replacements that spec out in the 120 AMP range. Pulling 10~20 amps through a heatsinked 50 AMP FET is pretty reasonable. If you ran into overheating issues or needed more capacity a 120 AMP FET would be more than enough.

I had a few of those coils burned out on my 85 gl. They actually are wired in series with taps in between. For low speed all three are used, next speed bypasses one and only uses 2 of the resistors etc. until high speed where they are all bypassed. I have a lot of coiled nichrome wire and cut some small pieces that I soldered in place. It's almost impossible to solder the wire because the nichrome repels instead of wetting the solder. I might try to plate the wire with copper if I get time. Then I could cut little coils and plate the ends and make them available.

I can't seem to find this blower resister either. Does anyone know where it is located on a 1981 EA81? Maybe this will help out The Sucker King as well.

Bump...

THAT'S why I don't have "1" !

thanks!

-Dok