My AC Guy Says I Have Mold in My AC
Your AC guy opens the air handler and says:
“You’ve got mold.”
Maybe.
There’s certainly stuff growing in HVAC equipment sometimes.
But unless your HVAC technician is qualified to identify it as mold, we’d be a little careful about making that declaration based solely on:
“Yep. That’s black stuff.”
What Can an HVAC Technician Tell You?
We can open an air handler and find visible growth on:
- evaporator coils
- drain pans
- blower assemblies
- insulation
- duct surfaces
- other damp areas
We can photograph it.
We can show you where it is.
We can explain why HVAC equipment provides conditions where biological growth may occur.
And we can address HVAC conditions that may contribute to moisture.
What we shouldn’t automatically do is look at something dark and announce:
“That’s toxic black mold.”
That’s a considerably bigger claim.
Black Doesn’t Mean “Black Mold”
This is where homeowners understandably get nervous.
Someone points at black material inside the air handler.
Then comes:
“You’ve got black mold.”
Then immediately:
“Luckily, we sell a $2,000 air purification system.”
Easy there.
Color alone doesn’t identify what something is.
EPA notes that determining the specific type of mold generally isn’t necessary in most situations, and if mold is suspected, the important issue is addressing the moisture problem and properly dealing with the growth. (epa.gov)
Does Growth Inside an AC Mean the Whole House Has a Mold Problem?
No.
An evaporator coil routinely gets wet.
There’s a drain pan underneath it.
It’s dark inside the cabinet.
Dust and organic material can accumulate.
That makes HVAC equipment a place where microbial growth can occur.
Finding visible growth inside the air handler does not automatically mean:
“Your entire house is contaminated.”
We need context.
What About a UV Light?
UV-C equipment can be useful in HVAC systems, particularly when it’s installed to continuously irradiate surfaces such as the evaporator coil and drain pan.
That’s a legitimate application.
But:
UV light is not a magic eraser for every moisture or mold problem in your house.
If you’ve got a water intrusion problem, fix the water intrusion.
If indoor humidity is excessive, figure out why.
If something needs to be physically cleaned, clean it appropriately.
We shouldn’t use an IAQ product as a substitute for identifying the underlying problem.
What Should You Ask?
If somebody tells you there’s mold in your AC, ask:
“How do you know it’s mold?”
And:
“Can you show me what you’re seeing?”
Pictures are particularly useful here.
If we’re recommending cleaning or another HVAC correction because there’s visible growth inside the equipment, you should be able to see what we’re talking about.
The Klein Answer
We may find visible biological or microbial growth inside HVAC equipment.
We’ll show it to you.
We’ll explain what conditions may be contributing to it.
And we’ll discuss what can reasonably be done about it.
But we’re not going to stare at some black stuff on insulation and suddenly become a laboratory.
Something growing in your air handler deserves attention.
It doesn’t deserve an instant horror-movie diagnosis.
Show the homeowner what you found. Fix the moisture problem. And leave the microscope work to people with microscopes.