Blower fan won't run intermittently in very cold temps

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RenKJ

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has anyone had an issue of the blower failing to run on any speed when the interior cabin is very cold (below -25c)

I've had this issue twice this winter, once it kicked on after driving a kilometer, and more recently it didnt kick on until I went over a decent bump in the road. This also happened intermittently last year during the same temps but it was pretty rare and usually came on after the engine was fully heated. Is it possible the fan is freezing from humidity and seizing?
 

Johnny O

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What year is your Jeep?
The KJs have a pneumatic based HVAC control. As a result, the rubber seal behind the main Vent Position Control switch outgasses and gets hard with age. The lack of a good seal on the micro pneumatics causes all sorts of weird stuff to happen. The good news is it is easy to get to and clean, then can be treated will a small amount of silicone based lubricant, like dielectric grease, to reestablish the seal.
 

RenKJ

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What year is your Jeep?
The KJs have a pneumatic based HVAC control. As a result, the rubber seal behind the main Vent Position Control switch outgasses and gets hard with age. The lack of a good seal on the micro pneumatics causes all sorts of weird stuff to happen. The good news is it is easy to get to and clean, then can be treated will a small amount of silicone based lubricant, like dielectric grease, to reestablish the seal.
I do have silicone wd-40 in the basement, going to take a look this week and follow up, I guessed it's not the resistor module as I didn't lose any particular fan level first, they just all cut out together when it happens
 

RenKJ

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Johnny O

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I do have silicone wd-40 in the basement, going to take a look this week and follow up, I guessed it's not the resistor module as I didn't lose any particular fan level first, they just all cut out together when it happens
Don’t use wd40! It gets sticky with age!
 

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