Smoke detector

I do home inspections for work which includes a fair amount of new houses. It's VERY common for detectors in new houses to alarm when I get in and start running the heat system and testing the appliances. There's a lot of dust that lands places during construction and then gets blown around for a bit. Also, lots of off gassing from finish coats on appliances, heaters, etc, etc. As others have said, replace the detector and just use the coach. I'd say there is a very good chance it will just go away after some time and usage.

His MH is new and most likely still under warranty guys. Take it to Fleetwood OP.
Actually mine went off when I was winterizing the RR ice maker. 1st thought was a warning about the door being open to long, but no it was the CO alarm.
Only time thus far.

That's he first thing I did was to replace the cheep SD (about $3) with one that cost $30 with smk and CO. Also did a fire drill with DW, she thought I was nuts, BUT thinking of getting out the bed rm window and landing on you head. Having a stick in closet to hold window, push matres to window, and go out backwards. Also replaced fire ex. with one big enough to put out a fire.

Anytime I have an issue with a smoke alarm I replace it - there not expensive and I wouldn't waste time diagnosing unless the replacement alarm gave same problem.

I think if the antifreeze is atomizing due to a pin hole leak in the heater core it might be possible. Try the test again but this time instead of turning the fan off spin the temperature dial to the full cold side. It might take a few minutes for the coolant pressure to bleed off once the control valve closes but if the core is leaking the alarm should shut off.

Also the heater core isn't a Ford product. The coach builders install them during house construction. Same with various parts of the dash AC.

Steam will activate SD.
I had it happen in my house when after hot whirlpool bath I open the door to hallway with SD in it.

vacuum off the alarm and remove the dust and it will should work.

I'm not sure how an antifreeze leak would get into your heating system.
I guess anything is possible.

First, I would replace or switch the smoke alarm that activates. If the replacement alarm does the same thing, you could be on to something with the antifreeze leak.

Maybe the alarm is bad.