Hello again.
I am wrestling with a common automotive problem. On many vehicles, the speed of the Blower Motor that circulates air inside the cabin of vehicles uses a Resistor Block consisting of various length and thickness windings of steel coil as resistors to vary the blower speed. (See photos 2 & 3 below)
The common problem is that there is so much heat generated in the process that the Resistor Block itself, along with connectors often fail in time due to the excessive heat. Connectors can be themselves be expensive costing over $100.00 for some vehicles. Generally, the resistor blocks themselves are not as expensive as the connectors.
One typical way in this particular instance to mitigate the problem is avoid using lower blower speeds as more current is resisted to achieve the voltage drop in order to get lower blower fan speeds (is that correct?) Using the higher speeds requires less current resistance (correct?)
There was a time these could be easily found in self service pick your own part automotive salvage yards. However, my vehicle is about 20 years old now and it's becoming rare to find a donor vehicle.
The usual fix for the Resistor Block is a simple buy and replace (readily available, cheap & easy)
But when the Connector itself has been damaged (as often occurs, See photo 1 immediately below), the fix is more costly and more involved as it involves cutting the pigtail and splicing in new wires and the new connector. Here is a picture of the damaged connector in my vehicle.
The damage is mostly on the Left side which probably corresponds to the connector with the highest current resistance.
I was able to exactly duplicate this connector using CAD design and successfully printed a duplicate on a 3D printer, but the problem is that even with ABS plastic, the copy produced on the 3D printer will not withstand the heat which I estimate to reach 325 F where the wire from the harness connects with the terminal on the Resistor Block.at times. The Glass Transition Temp of ABS used in 3D printing is only 220F.
Of course I can buy a new connector and it will last a few years. But I'm wondering if there's a way to mitigate the heat at the connector.
Here's two photos of the resistor block and it's connecting tabs where the plastic connector plugs in
My temporary solution is to eliminate the plastic connector altogether and instead, carefully wrap the end of the wire and each female connector with Kapton Tape and them simply push each wire onto the spade connector on the Resistor Block shown in the photo immediately above. The risk with that is the HOT wire coming off and contacting a ground in the engine compartment.
So what I'm looking for is a way to mitigate the heat at the connectors. Any ideas would be appreciated.
Thanks for your thoughts
I am wrestling with a common automotive problem. On many vehicles, the speed of the Blower Motor that circulates air inside the cabin of vehicles uses a Resistor Block consisting of various length and thickness windings of steel coil as resistors to vary the blower speed. (See photos 2 & 3 below)
The common problem is that there is so much heat generated in the process that the Resistor Block itself, along with connectors often fail in time due to the excessive heat. Connectors can be themselves be expensive costing over $100.00 for some vehicles. Generally, the resistor blocks themselves are not as expensive as the connectors.
One typical way in this particular instance to mitigate the problem is avoid using lower blower speeds as more current is resisted to achieve the voltage drop in order to get lower blower fan speeds (is that correct?) Using the higher speeds requires less current resistance (correct?)
There was a time these could be easily found in self service pick your own part automotive salvage yards. However, my vehicle is about 20 years old now and it's becoming rare to find a donor vehicle.
The usual fix for the Resistor Block is a simple buy and replace (readily available, cheap & easy)
But when the Connector itself has been damaged (as often occurs, See photo 1 immediately below), the fix is more costly and more involved as it involves cutting the pigtail and splicing in new wires and the new connector. Here is a picture of the damaged connector in my vehicle.
The damage is mostly on the Left side which probably corresponds to the connector with the highest current resistance.
I was able to exactly duplicate this connector using CAD design and successfully printed a duplicate on a 3D printer, but the problem is that even with ABS plastic, the copy produced on the 3D printer will not withstand the heat which I estimate to reach 325 F where the wire from the harness connects with the terminal on the Resistor Block.at times. The Glass Transition Temp of ABS used in 3D printing is only 220F.
Of course I can buy a new connector and it will last a few years. But I'm wondering if there's a way to mitigate the heat at the connector.
Here's two photos of the resistor block and it's connecting tabs where the plastic connector plugs in
My temporary solution is to eliminate the plastic connector altogether and instead, carefully wrap the end of the wire and each female connector with Kapton Tape and them simply push each wire onto the spade connector on the Resistor Block shown in the photo immediately above. The risk with that is the HOT wire coming off and contacting a ground in the engine compartment.
So what I'm looking for is a way to mitigate the heat at the connectors. Any ideas would be appreciated.
Thanks for your thoughts
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