Hi. If you have wondered how mold remediation in hvac systems. I suggest you read this article by Fortador. Visible mold on basement walls, carpet or drywall is a problem. However, having mold in your HVAC (heating, ventilation and air conditioning) systems is a serious danger to you, everyone living in your home and even your pets. When your furnace or air conditioner is running, a fan will turn on and the airflow will spread mold spores throughout your home if there is mold in your HVAC system.