Not sure this helps. Found this:

Sharp SKMD24F0AS

24 Inch Flush Mount Deflector Vent for Microwave Drawer

I know they are all rebranded from Sharp, but my Thermador drawer does not vent onto the cabinet below. You may want to call sharp and make sure this is what is supposed to be happening.

My Sharp doesn't vent down either, but I bought it 3 years ago.

Just a quick response to some of above. Sharp does make a "flush mount deflector" but the intended use for that is flush mount installations where the face / drawer front of the unit is truly flush w/ cabinet frames. In such a scenario you have to redirect the venting away from the cabinet bottom to outside (and then you're really back to my scenario). I half think a flush mount installation would be even worse - even more guaranteed to generate condensate that stays on the cabinet facing as opposed to going airborn.

I did call Sharp but the person I spoke to you was not a real expert in the product. I don't see myself being able to convince them to re-engineer the product and send me the revision.

But you may convince them that you need a different brand because of their design flaw. I would look at alternate brands in depth to see if they have similar issues rather than live with damaged cabinets.

Since mine is already installed, I'm not sure I see the return on effort to get a new unit, even if it's pretty easy to swap out (it is). Plus, I actually like the unit in all other respects so far. My original intent here was to see if anybody has any ideas about PROTECTION other than satin poly -- maybe I could turn the screws on Sharp if I found a kitchen appliance product manager.

Just had another idea. Could try using some of that clear 3M film used to protect car bumpers. I think it's easily removed (would need to test that, though I guess in 3 years it could be harder to remove and take paint with it -- repainting a little bit of cabinetry down the road is not end of world). Probably glossier than most cabinet finishes (my cabinets are more satin finish) but below the microwave may not be too visible.

Bagofchips,

Can you post a picture of this issue? I am not sure I understand what you are referring to.

I also don't know what a kitchen appliance product manager is.

I'll try to post a picture but I think it should be pretty clear. Verbally again for now: The microdrawer has airvents where moist air from cooking comes out. They are located on the BOTTOM of the unit, at the FRONT of the unit. The unit protrudes what? 1" or less from cabinets which means said moist air blows DOWN the faces / drawer / door fronts of the cabinetry beneath. (Most people have a drawer underneath.)

A kitchen product manager? Most consumer products companies have people called "product managers" whose job it is to live and breathe the business of their product or product line. Features, positioning in the marketplace, failures, marketshare, manufacturing costs all fall largely on them. They are basically running a business within the business.

I decided to check my 2-1/2 years-in-use unit yesterday. Turns out it does vent down (at least I can feel air when it's on) but I have never seen a single instance of moisture on the cabinets below the microwave.

No moisture here either after 3 years.

I am having this problem with my sharp microwave drawer. Only installed 2 months ago and I see the damage already on the cabinet underneath.

We have been having this problem since it was installed. now our beautiful wood below and on the sides of the microwave are stained.

I have this problem and after researching quite a bit, here's what I have found. This applies to the 24" MW drawer from Sharp. This is likely an installation problem. There are two types of installations, flush mount and not flush mount. the flush mount installation requires the steam deflector. Yours is the not flush mount installation. However, that instalation requires that the unit be mounted so that 7/8" of the SS side be showing. Mine was installed with 1/2" showing and that is causing the steam to collect on my lower wooden cabinet drawer. Check the installation specs against what is actually in your kitchen. This is called 'overlap' and the specs for the 30" unit are slightly different (23/32").