Before deciding to replace a coil, HVAC professionals use a series of checks to pinpoint the issue. Here’s how the process typically works:
1. Visual Inspection
Technicians start by looking for telltale signs:
- Corrosion or pitting on coil surfaces
- Refrigerant oil stains, which often indicate leaks
- Ice formation or frost buildup
- Dirty fins or blocked airflow
2. Temperature Differential Testing
Using thermometers or sensors, they measure the temperature drop across the evaporator coil. A healthy coil should show a significant difference — around 15°F to 20°F (8°C to 11°C) — between air entering and exiting. A low delta could mean the coil is no longer transferring heat properly.
3. Refrigerant Pressure Readings
If a technician suspects a leak, they’ll check system pressure. Low pressure on the suction side may suggest the evaporator coil is undercharged or leaking.
4. Airflow Testing
Restricted airflow can mimic coil failure symptoms. Technicians will inspect filters, ductwork, and fan speeds to rule out external airflow issues before condemning the coil.
5. Leak Detection
Using electronic detectors, dye kits, or nitrogen pressure testing, they identify any breaches in the coil’s tubing — especially around soldered joints or bends.
6. Coil Age & Service History
Even if a coil is functioning but over 10–15 years old, heavily corroded, or has required multiple repairs, replacement is often the smarter long-term choice.
At KCL, we collaborate closely with service technicians, building operators, and mechanical contractors to make sure the replacement coil is precisely matched to the diagnosed issue — not just guessed at.