Sean came out and gave the AC a look-see. It's a "gas-pack" which means that the heat and AC are in one unit.
Sean came into the house and smelled the "STANK". Took off the covers and showed me the guts of the unit.
Nothing exciting. No standing water, insultation was dry, AC coils fairly clean. I stuck my head in and sniffed around. Nothing obvious. I put my nose right on the coils and took a whiff. Faint odor there so he squirted on a coil cleaner/deodorizer, even though he felt that wasn't the problem.
We talked about the attached humidifer and we both felt that might be the culprit. Down under he went...he noticed a ductwork whose strap had broken and fixed that. He got over to the humidifer and said that water was coming out of it...which it shouldn't. He declared it "broken" and unplugged it and yanked out the filter which was supposed to be changed every year by the service company.
We didn't know that and it appears that they didn't know we had a humidifer, even though they installed it.
Anyhoo...I took a bit of a sniff at the filter expecting to say "Bingo!". Nope... that wasn't it.
He said the ducts were dry and he didn't see any mold. So it's a mystery!
He offered up suggestions on "what's the next step".
We could do a whole house duct cleaning. (SM called around and has us set up for next Monday for $99)
If it's still STANKY then we're looking at replacing the duct work ($ouch$).
In the mean time, I sprayed Febreeze on the air filter which made the house instantly smell like Febreeze. I'm planning on running the AC all day today to try and see if it disapates.
Sean, thinks it's the humidifer, and that the STANK will eventually fade away now that it's disconnected.
Me...I'm not so sure. Time will tell though. It will either fade away or we'll be climbing the "problem" ladder eliminating issues until it does go away.
At least it's not mold.