I am in heating season for the past week and it smells like a skunk in my ducts and where the blower motor sits. It is especially noticeable when I come home from work and the house has been sitting all day. Read another forum where someone had the EXACT same problem after having blower motor replaced. My motor was replaced 3 months ago. It seems to only be an issue now that I am heating. I have SCRUBBED the coil with vinegar, bleach and professional "Coil-Rite". The coil DOES NOT SMELL. The smell is down at the blower. Is there a rubber bushing or something the blower sits on. I've smelled this smell before on thick black rubber bushings... totally unrelated to HVAC. No there is not a dead skunk under the house. The odor has decreased these past 2 days because I was back on cooling mode since it got hot out.
This lead me to my second question... In the quest to find the odor I noticed the step down transformer is SUPER HOT. Like can keep your finger on it for 20 seconds but then it hurts too much. The transformer cools down when the blower kicks on because of the air flow. But if the unit just sits and the house stays at a temp that doesn't call the unit for like an hour or two it gets REAL HOT. However it functions fine. Local HVAC guy who did the motor install didn't seemed concerned about the transformer being THAT hot and other than a coil cleaning had no idea on the odor per our phone conversation.