I work in a busy office in FL. We have spent much money fixing AC, cleaning/replacing ducts... even tried cleaning out plumbing. Roof has been replaced, wallpaper taken down, carpet cleaned... AC still stinks... Doc says like sewer... I say like stinky feet. Building is very old much work has been done recently. AC is about 7 yrs old, started smelling 5 months ago. Anyone out there ever dealt with this problem? I appreciate any suggestions.

Our office has our air handler in the attic portion of the building. Each year we have to get a shop vac and suck out the algae growing in the condensation drain line. There is usually a pvc pipe that is located near your outside unit that drains the condensation. We have made an attachment for our shop vac that allows us to get a good suction on the small pipe. You might have some algae growing in your a/c drain pan that is giving off the smell or it is blocking the drainage and the stagnate water might be doing it. I have also seen a recommendation on a DIY show that says to run a cup of bleach through this line at the beginning of the a/c season.

Have you had the premises checked for mold?

Yes, we have had the place checked for mold. I will ask our AC guy if he's cleaned the drain pipe. Thank you for your answers.

Dirty socks syndrome. It happens to many units. The indoor A/C coil needs to be cleaned with a chemical wash. Call your local HVAC company they should know exactly what to do.
In the biz we used a product made by NuCalgon. It worked wonders and kept the coil free of bacteria/mold and other smell causing items. It is safe to breath the air right after usage so there is no long shut down time as with some other cleaners.

Our AC guy says he washed coil, but now wants to take it out and run system to see if smell persists. My boss is reluctant because of all the money that she has already sunk into this problem without any resolution to the smell. I'm hoping to find her a trifty solution before full summer hits Florida. Thank you for your answer.

Removing the coil for a cleaning can get very expensive,, has to be done by a HVAC tech,to remove freon,take coil loose resolder,vacuum out with vacuum pump refill with freon,, has to be a licenced tech., to cheap way to do that,,