Blower resistor on Dodge

I just had the second blower voltage divider fail on my van, and thought I would post about this.

This divider provides the multiple fan speeds, and is installed in the air conditioner intake plenum.

When I first bought the car, the connector had burned through, and the resistor was damaged.

So, I cobbled up an ersatz connector (new pigtail apparently not available from Chrysler) and installed a new resistor.

This one lasted a couple of years. The connector survived. When I removed the divider, I found that there were three nichrome coil resistors and one little ceramic unit. The ceramic unit (about 0.1 ohm resistance) apparently functions much like a fusable link, and mine was open.

I cut the thing out of the circuit, soldered a 20 amp fuseholder across the terminals (and outside the plenum), and put it back in service.

It works fine. I can , if I have another problem, just replace the fuse. This will soon tell me if the current to the blower motor is spiking and causing the ceramics to fail. It might be hard to find otherwise as it is probably intermittent.

I have an extra factory resistor, and when I am satisfied that all the kinks are out of the system, I will return everything to OEM, maybe. This seems to be a weakness with certain Dodges.

It may require a blower motor to fix it. Oddly, a motor from the dealership is $33. From NAPA or Autozone, it is considerably more expensive.

Just thought this might help someone down the line.

Reply to
<HLS
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Reply to
tim bur

If the resistor pack doesn't last... you either have a blower motor that drawing too much current... or there is insufficient airflow over the resistor pack... or both.

Professor

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Reply to
Professor

I suspect the blower motor. It has never blown a fuse while operating at full speed however.

Fusible resistors sometimes just 'relax', from vibration, age, whatever.

These Dodge models seem to have a problem with this setup. When I first experienced the problem, I couldn't get the burned connector pigtail from Dodge, so went to the junkyards. Never found a connector there as they were all scavenged. This lead me to believe that something wasn't quite right with this setup.

I noticed this resistor pack is not soldered internally, but rather is crimped together. Not an unusual construction technique where heat is expected, but the terminals were not necessarily still tight in the crimp either. That can be a source of problems.

I can monitor the current drain through this resistor pack now by measuring the voltage across it. Knowing that the total pack resistance is about 2.2 ohms, it's easy to measure as a function of voltage.

I wanted to dig into this installation and find out what makes it stop ticking.

Reply to
<HLS

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