Focus on preventing condensation and continuous high humidity. Damp dust on any surface will grow mold, including steel and glass. Any material touching a cold surface may have condensation while cold. As coils condense moisture but do not grow mold because the dust is washed down the drain, other surfaces do not wash themselves.
Provide clearences between air handler and the drywall. Have a couple hours of blower operation everyday to dryout the entire airhandler and all surrounding areas. Monitor your %RH in all areas within the home. Maintain <50%RH during the non-heating season. For indoor air quality provide enough fresh air throughout the year to purge indoor pollutants and renew oxygen. During cool wet times of the year in green grass climates, you will need supplemental dehumidification to provide the basics for indoor air quality. Regard TB
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"