Care for some mold with that a/c?

By Elizabeth Kuster  | July 8, 2011 - 11:49AM

Ah, summer. The halcyon time of bright sunny skies, long sweaty days and, um...air-conditioner mold.

“My super just told me that two of our [A/C] units have mold," one apartment dweller confesses on "Strangely, they are the two newer units. He thinks the problem is that our built-ins around the units are made of Sheetrock rather than wood, and therefore hold the moisture and encourage mold. His suggestion was to rip [those] out and replace them with wooden built-ins. I've never encountered this before. What do I do?” 

Luckily, several commenters have words of wisdom to offer, starting with the Yoda-like observation, “No reason to panic. There are over 100,000 types of mold. You can grow mold on a piece of bread in two days. The mold you hear about that is really toxic are types that grow on wood, paper, drywall, etc.” 

Another commenter observes, “It's those newer ‘wall’ units that are most prone to mold, since the contractors in many cases cheaped out and didn't put backs on them, leaving the exposed drywall inside the unit vulnerable to condensation—and eventually mold.”  (Case in point: This rather fascinating on-the-job video by a Manhattan contractor hired by a condo owner to right a bunch of new-construction wrongs.)

And another commenter wonders if perhaps the moldy A/C units in question are too powerful for the size of the room they’re in, “which could result in higher humidity in the air”—a comment which prompted someone else to encourage the mold-sufferer to find an “online calculator that takes several inputs to determine BTU needs.” (We like the one on

Other advice includes:

● “Get a hygrometer (it’s like a thermometer, but measures humidity; they're cheap enough) and determine how humid your apartment is. You may want to invest in a dehumidifier.”

● “Air-Wave will come and do a 'spring cleaning’ and also tell you if [your A/C units] need to be taken out and subjected to a more rigorous cleaning.”

● “I had a Friedrich wall unit and had it serviced. They took it out and steam-cleaned the unit. If there [was] any mold, the steam should have killed it....”

● “Check your condenser water line. If it is a heat pump, there should a plastic hose dripping water into a pan which goes into wastewater riser. In [both] wall A/Cs and PTACs, the water should not be pooling; it should be draining out of the building.”

And speaking of PTACs—those self-contained heating-and-cooling units located radiator-style against the wall—BrickUnderground would like to remind you that it’s time once again to get those puppies cleaned out.

“NYC apartment owners tend not to realize that PTAC units require twice-yearly maintenance, and that as the owner of the apartment, it’s their responsibility," mold remediator Jeff Gross, a senior vice president at the Manhattan-based property damage restoration company MAXONS Restorations explained in a recent BrickUnderground post, Is your apartment making you sick? Top 3 places to look for mold.

The most common mistake PTAC owners make: “The filter is not replaced often enough,” Gross explains. “Dust collects on the filter and on the coils, and through condensation it drips into the condensate pan and clogs the drain. Then the condensate pan overflows and leaks under the floor.”  Read all about it here.

A final word of warning: A/Cs aren’t the only culprits when it comes to household mold. Front-loading, high-efficiency washing machines can also harbor mold, especially in hot, humid weather. To help stay spore-free, always keep your washing machine’s door open a crack when it’s not in use, and leave the door wide open when you go on that much-deserved summer vacation. 

(; previously)

Related posts: 

Is your apartment making you sick? Top 3 places to look for mold.

More pressure to man up against mold

Why your high-efficiency washing machine smells like cat pee

New condos called 'sickest' buildings in NYC


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