4 Wheel Drive/SUVs: 4 wheel drive not engage in cold weather, jeep yj, vacuum system

Question
QUESTION: I have a '93 jeep yj sahara. it uses a vacuum system to engage the four wheel drive on the front axle and it will not engage whenever it is cold outside. the indicator light on the dash still comes on. we get some extreme winter weather here so it was parked all winter. now that it has warmed up it shifts in and out without a problem. i have thought about replacing the vacuum system with a posi-lock but i would rather not have to spend the money to buy one. thanks

ANSWER: Do you think that the vaccum pod is freezing up? Where are you from?


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QUESTION: i live in Moscow, id. whenever i had problems it was always below 30 degrees and often times it was below 20. how would i know if the pod is freezing?

Answer
It is possible that it may be freezing due to condensation maybe getting it to it, We have replaced some of those in the past, just like anything its hard to try and fix it without putting my hands on it, but that would be someplace to start thansk and sorry I couldnt be of more asistance ADAM