Auto Air Conditioning & Heater Repair: Dodge Blower Motor, continuity check, lengthy periods

Question
On my 2004 Dodge 2500 pickup the air conditioner/heater blower motor turns off for lengthy periods of time, without turning it on or off by the switch.  You can try to turn the switch attempting to turn it back on, but it will not respond, then all of a sudden if the switch has been left on, or to its highest speed, it will come back on.  Cannot figure out if the blower motor itself needs replacing or could there be some other cause?  Thanks

Answer
Danny,
It sounds as if this is as simple as having a loose connection on the fan itself. Being that according to your wiring diagrams, the circuits find their ground path through the resistor block. Your resistor block is located on the bottom of your blower motor housing under the passenger side dash panels. You should be able to access it without removing anything other than the cover. Check the resistor block outlet plug connectors for continuity from the terminals to ground. If that checks out good, do a continuity check between each of resistor block inputs and the output to the fan. Your resistor block itself may be bad  and in need of replacement. The reason I say this is because you specifically stated the highest speed works, but did not mention the lower speeds. If the lower speeds do not work at all, then it is definitely this resistor block.

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