AC System Assessment
Comprehensive AC system assessment procedures including visual inspection checklists, refrigerant charge verification, airflow assessment, electrical testing, and performance benchmarks.
- Perform a systematic visual inspection of residential AC systems
- Identify common AC installation deficiencies and their performance impacts
- Measure and interpret key AC performance parameters
- Document assessment findings and prioritize recommendations
Lesson 1
Visual Inspection & System Documentation
The BPI Assessment Approach
A BPI AC system assessment is not a simple equipment check - it is a comprehensive evaluation of the entire cooling system within the context of the building. The assessment determines whether the system is properly installed, correctly charged, delivering adequate airflow, and matched to the building's actual cooling load. Every finding is documented and used to prioritize improvements.
The assessment begins with documentation of the existing system before any testing:
Equipment identification - Record the outdoor unit manufacturer, model number, serial number, nominal capacity (tons), refrigerant type, and date of manufacture. Do the same for the indoor unit (air handler, furnace, or coil).
Installation date and age - The serial number typically encodes the manufacture date. Residential AC equipment has an expected service life of 15-20 years. Systems approaching end-of-life may justify replacement rather than repair.
Previous maintenance - Ask the homeowner about service history, recent repairs, and any comfort complaints.
Outdoor Unit Inspection
The outdoor condensing unit is inspected for:
Condenser coil - A dirty condenser coil raises head pressure, reduces capacity, and increases energy consumption. Even a thin layer of dirt, cottonwood seeds, or grass clippings can reduce capacity by 10-20%. Severely blocked coils can reduce capacity by 30% or more.
Clearances - The condenser needs adequate airflow around it. Vegetation, fences, or stored items too close to the unit restrict airflow and raise head pressure. Most manufacturers require 12-24 inches of clearance on all sides and 48 inches above.
Refrigerant line insulation - The suction (large) line must be insulated from the outdoor unit to the indoor coil. Missing or deteriorated insulation allows the cold suction line to gain heat, reducing efficiency and potentially causing condensation that drips onto ceilings or walls.
Physical condition - Look for rust, physical damage, settling or tilting of the pad, and vibration damage to refrigerant lines.
Indoor Unit Inspection
Evaporator coil - If accessible, inspect for dirt accumulation on the air-side face. A dirty evaporator coil restricts airflow and reduces capacity. In humid climates, a dirty coil can become a breeding ground for mold and bacteria.
Condensate drain - Verify the primary drain is clear and flowing. Check for a secondary drain or overflow switch. A clogged condensate drain can cause water damage and, in humid climates, backup of condensate into the duct system.
Filter - Note the filter size, type, MERV rating, and condition. A clogged filter is the most common cause of low airflow and high static pressure. Record when the filter was last changed.
Ductwork connections - Check for disconnected ducts, poorly sealed joints, and missing insulation at the air handler connections.
The Dirty Filter Problem
A clogged 1-inch filter can add 0.20-0.40 IWC of static pressure to the system. This is often enough to reduce airflow by 100-200 CFM on a 3-ton system, causing coil icing, reduced capacity, and high energy bills. Always check the filter before diagnosing any performance problem.
A BPI AC assessment starts with thorough visual inspection and documentation of both indoor and outdoor units. Key inspection points include condenser coil cleanliness (dirty coils reduce capacity 10-30%), refrigerant line insulation, condensate drain function, filter condition, and physical clearances. Document everything before moving to performance testing.