Theories needed:temp controlled chest freezer causing head space to fill and overflow

I have a weird issue that happens when I temp control. I would love to have a time lapse camera on my temp readout and on the carboy so I could actually see what is causing it.

I use a chest freezer with a Ranco 2-stage temperature controller. The freezer and some fermwrap are plugged into it. The thermoprobe goes into a thermowelled stopper down into the beer.

Here's what is happening. It occurs in one of the following situations. I don't know which one.

1)The temperature goes up and then the freezer kicks on to bring down to the set temperature. The headspace fills up and kraussen comes out through the airlock.

or

2)The temperature goes down and then the fermwrap kicks on to bring up to the set temperature. The headspace fills up and kraussen comes out through the airlock.

I am unsure which is causing it but trying to understand what is actually happening. Any ideas?

On a completely unrelated note, have you ever stuck your head down into the freezer after a few days of vigorous fermentation and inhaled? Wow!

I think I might be able to help. I was in the same boat as you. Although I don't have krausen coming out of the airlock (fermcap, love it) I have had a persistent banana fruity ester flavor in my beer that I am not a fan of.
I have a chest freezer with the same 2 stage ranco controller as you. I have a desk lamp with a lizard heat lamp in it. My thinking was to set the temp controller to have a 2 degree swing where the freezer would kick on at a certian temp and the lizard lamp kick on when it got below a certian temp.
Here is where I think I (and maybe you) went wrong. When the beer temp where the thermowell is located gets low and the fermwrap kicks on, it heats up the beer on the edge of the bucket/carboy causing the yeast to "overwork" for lack of a better term until the beer gets back up to the set point, causing esters for me and a ton of krausen for you. I see you are in Seattle, so you are pretty temperate year round (?). Try skipping the fermwrap and just let the freezer come back up to your set temp. I think it's better to for the yeast to get a little too cool than a little too warm.
My next batch in the fermenter (or is it fermentor?) will be the first batch without the heat lamp so everything I just typed is just conjecture. It is Revvy's Kiss Yer Cousin Kentucky Rye Ale and I am excited that this will be my first non "banana" beer.

Hope this helps.

I forgot to add that I use fermcap this time. Still the same issue. I have never had the banana/fruity ester flavor in my beers that you are encountering. I will try the next time to not use the fermwrap during the active fermentation. I mostly use it anyway to bring up the temp near the end of fermentation to perform a diacetyl rest for all my beers anyway.

My buddy also mentioned that it could "possibly" be the chest freezer itself. Perhaps during a chill cycle the compressor is causing the chest freezer to vibrate and causing excessive agitation or CO2 to come out of solution? All conjecture. I will first try removing the heat wrap from the early stages of the fermentation as a variable. I will post back what I find. Cheers!