Our new Cougar travel trailer gets a very strong formaldehyde(?) odor when it sits in the sun closed up (except for some windows cracked open). My wife has asthma and this smell triggers it to the point she can't be inside, it is strong enough to burn my eyes and nose as well. Airing it out only helps short term. I have read about using the furnace on full for 12-24 hours, then venting, and using ammonia to neutralize the smell. Question is what strength ammonia, and where can I get it. Will try the heat method first, but want to be ready to use ammonia if that isn't enough. Thanks.