How to Deal with Odors in Rooftop Air Conditioning Units

Rooftop air conditioning units (RTUs) play a crucial role in maintaining indoor air quality and comfort in commercial and residential buildings. However, unpleasant odors from these systems can create discomfort, reduce air quality, and even indicate underlying mechanical issues. If your RTU is producing foul smells, it’s essential to identify the root cause and implement effective solutions. Here’s how you can tackle odors in rooftop AC units.

1. Identify the Source of the Odor

Before addressing the problem, it’s important to determine what’s causing the bad smell. Common sources include:

• Mold and Mildew: Moisture buildup in ductwork, evaporator coils, or drain pans can promote mold and mildew growth, leading to a musty odor.
• Clogged Drain Lines: If condensation isn’t draining properly, stagnant water can develop foul smells.
• Dirty Filters: Clogged air filters trap dust, debris, and bacteria, which can cause unpleasant odors.
• Burning Smell: A smoky or burning odor may indicate electrical problems, overheating components, or dust burning off heating elements after prolonged inactivity.
• Biological Contaminants: Birds, rodents, or insects may nest in or near the unit, leaving behind waste that produces foul smells.
• Chemical Smells: A chemical or rotten egg odor could indicate a refrigerant leak or gas leak, which requires immediate professional attention.

2. Perform Regular Maintenance

Routine maintenance is key to preventing and eliminating odors. Ensure the following steps are part of your AC maintenance plan:

• Clean or Replace Filters Regularly: Dirty filters trap contaminants that can cause bad smells. Replace them every 1–3 months, depending on usage.
• Inspect and Clean Evaporator and Condenser Coils: Mold, mildew, and bacteria can accumulate on coils. Use a coil cleaner or schedule professional cleaning.
• Flush Drain Lines and Pans: Ensure that condensation drains properly to prevent standing water and bacterial growth.
• Check for Refrigerant Leaks: A professional HVAC technician can inspect for leaks and refill refrigerant safely.
• Seal Ductwork Leaks: Leaky ducts can pull in odors from outside or unconditioned spaces. Sealing these leaks helps prevent contamination.

3. Use Odor-Eliminating Solutions

• Install UV Lights: UV germicidal lights help kill mold, mildew, and bacteria inside the unit.
• Use Air Purifiers or Odor Absorbers: Activated carbon filters and air purifiers help remove lingering smells.
• Apply Antimicrobial Treatments: Treating ductwork and coils with antimicrobial solutions prevents microbial growth.

By identifying and addressing odor sources early, performing regular maintenance, and using odor-eliminating solutions, you can keep your rooftop AC unit fresh and efficient. If persistent odors remain, consult an HVAC professional for a thorough inspection.