So I went through the replacement process of the H3's heater motor resistor and harness. Easy enough to fix. Any idea why these burn out and short?

 

do some reading,searching. thats been posted a million times,next to leaky radiator.
if you spend some time rereading the forum most everything has been talked endlessly.
btw the resistor assm rarely ever is bad, its the connector and the fix is ez, read on!

and a short is when two wires touch when they shouldnt, rare too in that area.

 

Thanks for the helpful reply (see eyes rolling).

What would have been appreciated would have been an answer such as: "The problem is a loose connection in the connector between the resistor module and the wiring harness. The loose connection causes overheating of the harness, connector and module. The connector then melts and shorts out the resistor module which means that you loose the speed control.'

 

so you already knew the answer. good that you did
but nothing "shorts out " anything, that is an erronious term used to cover "all" electrical malfunctions.
i was just suggesting you read what you must have b4 you asked??
in this case it "opens" the connection, not short.
most guys fix it with just one new faston connector.