Preventive Maintenance

Preventive maintenance is scheduled work that keeps equipment operating safely and near its rated performance, and catches developing faults before they become no heat or no cool calls.

1. 1Replace or clean the filter and note its pressure drop.
2. 2Inspect and clean the condenser and evaporator coils as required.
3. 3Check the condensate drain, pan and safety switch, and clear the trap.
4. 4Measure capacitor microfarads and contactor condition.
5. 5Measure amp draw on compressor and fan motors against data plate values.
6. 6Measure superheat or subcooling and compare to manufacturer targets.
7. 7Measure supply and return temperatures and confirm a reasonable split.
8. 8Verify thermostat operation and staging.
9. 9Record all readings.

1. 1Replace or clean the filter.
2. 2Inspect the heat exchanger, burners and flame pattern.
3. 3Clean the flame sensor and measure the microamp signal.
4. 4Verify inducer and pressure switch operation.
5. 5Measure gas supply and manifold pressure against the data plate.
6. 6Perform combustion analysis and measure draft.
7. 7Verify temperature rise is within the manufacturer range.
8. 8Confirm all safety controls operate as intended and test carbon monoxide alarms are present.
9. 9Record all readings.

Visual inspection catches obvious problems. Measured readings compared with the previous visit catch trends: a capacitor drifting down, superheat creeping up, static pressure rising as a coil loads. That is the difference between maintenance and a look around.