Before you start

• •Maintenance agreement on file — confirm covered scope before arrival
• •Coil cleaner (foaming no-rinse for evaporator, fin comb for condenser)
• •Calibrated manifold gauges
• •Replacement filter (correct size — pull from truck stock or pre-ordered)

The procedure

Step-by-step, in order. Each step has the action and the reason it matters.

1. 1

   Indoor unit first — start at the air handler or furnace

   Inspect evaporator coil for dirt, mold, or ice residue. Clean with no-rinse foaming coil cleaner — spray and let drain. Check condensate drain — must flow freely. Pour 1 cup of water in pan; confirm it exits the drain. Clear with wet-vac if sluggish.

2. 2

   Replace filter — document size and MERV rating

   Replace filter regardless of appearance. Record size (e.g., 16x25x1) and MERV rating on ticket. Upgrade recommendations (MERV 8 → MERV 11) are a billable upsell and improve system efficiency. Never reuse a filter on a PM visit.

3. 3

   Measure static pressure

   Drill ¼" test port if not already present (charge separately). Measure supply and return static. Total static pressure over 0.5" WC on a standard residential system indicates restriction — dirty evap coil, undersized duct, or wrong filter.

4. 4

   Outdoor unit — inspect and clean condenser coil

   Clear vegetation within 18" of unit. Rinse condenser coil from inside-out with garden hose — low pressure, not power wash. Straighten bent fins with fin comb. Inspect refrigerant line insulation for cracks; replace any 6"+ section that is missing insulation.

5. 5

   Electrical checks

   Measure capacitor μF — document on ticket. Check contactor: pitted or burned = replace now (cost is minimal, callback is expensive). Check disconnect fuses with amp clamp for balanced loading. Check all wiring for burned insulation at the contactor.

6. 6

   Refrigerant check

   Connect gauges. Document suction/discharge and calculated superheat or subcooling. Do NOT top off refrigerant without diagnosing the leak. A properly functioning system does not lose refrigerant — topping off without leak diagnosis fails within 12 months.

7. 7

   Cooling efficiency check

   Run system 10 minutes. Measure supply temp at nearest register and return temp at air handler. Delta-T (return minus supply) should be 16-22°F. Under 16°F with correct charge = dirty coil or low airflow. Over 22°F = low charge or metering device issue.

8. 8

   Document findings, present report to homeowner

   Use a written or digital report — list every check, pass/fail, and any advisory items. Homeowner signature on the PM completion form. Findings presented at the door, not sent by email later. Service agreement customers who see the report renew at 85%+ rates.

Verify when done

• ☐Condensate drain tested with water pour — confirmed clear
• ☐Capacitor reading documented with pass/fail vs nameplate
• ☐Contactor inspected — condition documented
• ☐Delta-T measurement documented
• ☐PM completion report signed by homeowner

Common mistakes

• ✕Skipping the condensate drain test
• ✕Adding refrigerant without leak diagnosis
• ✕Not straightening condenser fins — causes 5-10% efficiency loss
• ✕Delivering findings by text instead of face-to-face — kills renewal rates

Trainer notes

The condensate drain check is the most commonly skipped step on PM visits and produces the most callbacks (water damage, mold complaints). Test it with water every time — never just look at it.

Common questions