They drilled for samples,  found Bunker C oil, ...

But I think it would take a coil cleaning, coil replacement and/or new ducts to truly remedy the problem because when the system turns on after having been off for an hour or so it blows air with a subtle hint of stale tobacco smoke.

Works great...coils versus glass flat top.Goal:Met...I provide my family and my customers with a nice clean, comfortable guest house that is close to the beach, is quiet and is convenient. 

@Rodney MorrisThe 2000 for the AC was just a new 2 ton unit and coil for the furnace, I believe it was a 14 seer, but the actual unit was probably around 1000, and then a few hundred for the other materials the rest went to my contractor, I am fortunate that one of my GC's is a licensed HVAC tech too.

I replaced this coil less than 6 months ago. 

The refrigerator is new, stainless, and so is the sink, but I replaced the 1980s electric cooktop with a wide coil stainless Frigidaire cooktop from the 1950's.

I just had both A-Coils for HVAC pulled out within the last 6 months..cleaned and recharged..no leaks were present per my HVAC guy and Condensers serviced.

Yes, the A/C condenser, coil, and furnace will replaced; those will be done by a separate HVAC company.

The new house would have in-floor heat and a piggy backed combi-coil for potable water....a very efficient system. cabinets are all straight with no bends so counter tops are dead simple and cheap.

I have cleaned behind and under every appliance, the dryer vents, AC coils, AC registers, and in other areas that had not been cleaned in a long time.