Condensation running down my range vent into my microwave in cold weather? (And cracks in ceiling)

[Wash. state Desk Jet]

22. The last time I ran into that problem

over a phone call in a house I remodeled about 14 year prior ,I thought about all the possibles.
Nightmarish. As it turned out it was up on the roof the vent needed sealing. The problem was far more simple than would have been expected. A $20.00 can of roofing sealant did the trick.

i decided to rule out the plumbing stack and vents up on the roof before I started looking around up in the attic or removing the micro wave to start the trouble shooting process.
And yes air got in there too ! Same problem micro wave and cracks ! I wonder if you thought about the vent or vents up on the roof !
In this case the plumbing vent was not very far away form the kitchen vent . The bathroom was behind the the kitchen back wall.Downstains bathroom and mini kitchen directly below in a straight plumbing line. The kitchen exhaust vent, I had the roofer install during the remodel.

Simply it came down to roofing maintenance. A can of sealant.

On that same remodel I threw up ply wood up in the crawl space for storage -so the possibilities were endless as to what the problem could have been. It came down to basic maintenance on the roof. Simple.

They described to me over the phone the same as you wrote- it started out a little and got worse over time. Usually visible after it rains.


Good luck with your project.
Merry Christmas !