Hvac Checklist for Preventive Maintenance

Standard Operating Procedure: HVAC Preventive Maintenance

1. Document Control & Revision History

---

2. Executive Summary & Scope

2.1 Purpose

This Standard Operating Procedure (SOP) defines the mandatory operational protocol for executing Preventive Maintenance (PM) on Heating, Ventilation, and Air Conditioning (HVAC) systems across all enterprise facilities. Adherence to this protocol ensures maximum asset availability, reduction of catastrophic failure risks, optimization of energy efficiency, and strict compliance with environmental and occupational safety mandates.

2.2 Operational Boundaries

This procedure applies to all commercial split systems, rooftop units (RTUs), variable air volume (VAV) boxes, modular air handling units (AHUs), centrifugal and screw chillers, and associated cooling towers. It encompasses semi-annual and annual maintenance cycles executed by internal facility technicians or certified third-party vendor contractors.

2.3 Regulatory & Industry Standards

Operations governed by this SOP must comply with the following standards:

• ASHRAE Standard 180-2018: Standard Practice for Inspection and Maintenance of Commercial HVAC Systems.
• ASHRAE Guideline 0-2019: The Commissioning Process.
• EPA Section 608: Clean Air Act regulations regarding refrigerant containment, recovery, and recycling.
• OSHA 29 CFR 1910.147: The Control of Hazardous Energy (Lockout/Tagout).
• NFPA 90A & 90B: Standard for the Installation of Air-Conditioning and Ventilating Systems.

---

3. Prerequisites & Tool Requirements

3.1 Mandatory Certifications & Training

• EPA Universal Certification: Required for all personnel handling regulated refrigerants.
• OSHA 10-Hour / 30-Hour General Industry Certification.
• NFPA 70E Standard for Electrical Safety in the Workplace certification (Qualified Electrical Worker status).
• OEM-Specific Certifications: Factory-authorized training for proprietary control systems (e.g., Trane Tracer, Johnson Controls Metasys).

3.2 Required Personal Protective Equipment (PPE)

• ANSI Z87.1 compliant safety glasses with side shields.
• ASTM F2413 compliant electrical hazard (EH) safety-toe footwear.
• Cut-resistant work gloves (ANSI Cut Level A4 minimum).
• Arc flash protection gear (NFPA 70E Hazard Risk Category 2 minimum when accessing live electrical panels).
• Half-mask respirator with P100 particulate filters (for coil cleaning and mold/pathogen mitigation).

3.3 Diagnostic Equipment & Tools

• Digital manifold gauge set with low-loss fittings.
• Clamp-on digital multimeter (True RMS) with calibrated leads.
• Anemometer and balometer for airflow verification.
• Digital non-contact infrared thermometer and contact thermocouple probes.
• Combustion analyzer (for gas-fired heat exchangers).
• Ultrasonic leak detector and electronic refrigerant sniffer.
• Digital micro-ohm meter / insulation resistance tester (Megohmmeter).
• Coil fin comb set, industrial pressure washer with chemical injector, and non-caustic coil cleaner.
• Computerized Maintenance Management System (CMMS) mobile terminal for record entry.

---

4. Roles & Responsibilities (RACI Matrix Table)

• R - Responsible: The role that performs the activity.
• A - Accountable: The role with final approval and fiduciary ownership.
• C - Consulted: The role providing advisory input or technical expertise.
• I - Informed: The role kept updated on progress and completion.

---

5. Step-by-Step Operational Procedure

Phase 1: Pre-Execution Safety & Administrative Protocols

• 1.1 Verify CMMS work order details, confirm asset ID, and review historical failure logs for the targeted HVAC unit.
• 1.2 Conduct a mandatory Job Safety Analysis (JSA) and toolbox talk with all participating technicians.
• 1.3 Isolate the equipment power supply utilizing OSHA-compliant Lockout/Tagout (LOTO) procedures at the master disconnect and motor control center (MCC).
• 1.4 Affix serialized lockout tags and personal padlocks; verify zero energy state using a calibrated multimeter.
• 1.5 Secure work area perimeter with safety cones and warning signage if located in public or high-traffic zones.

Phase 2: Exterior Inspection & Mechanical Integrity Assessment

• 2.1 Inspect structural integrity of unit base, curbs, isolation springs, and seismic restraints for rust, cracking, or displacement.
• 2.2 Inspect weather-stripping, access panel latches, and gasket seals for degradation, air leakage, or moisture intrusion.
• 2.3 Verify condensate drain pan integrity, proper trap pitch (minimum 1/4 inch per foot), and ensure drain lines are clear of obstructions and bio-growth.
• 2.4 Inspect ductwork transitions, flexible connections, and external insulation for tearing, sagging, or thermal bridging.

Phase 3: Air Distribution & Filtration Subsystem Maintenance

• 3.1 Remove existing air filters and log disposal/replacement in accordance with environmental protocols.
• 3.2 Install new OEM-specified filters (MERV 13 minimum for commercial applications), verifying proper airflow direction arrows and seal integrity to prevent bypass.
• 3.3 Inspect blower motor, housing, and wheel assemblies for debris accumulation, balance issues, and structural fatigue.
• 3.4 Check blower belt tension and alignment using a belt-tension gauge; adjust deflection to manufacturer specification (typically 1/64 inch per inch of span).
• 3.5 Inspect belt condition for fraying, glazing, or cracking; replace matching sets if wear exceeds tolerances.
• 3.6 Lubricate motor and blower bearings using manufacturer-specified synthetic grease via Zerk fittings (avoid over-greasing).

Phase 4: Coil, Heat Transfer, & Ventilation Subsystem Servicing

• 4.1 Inspect evaporator and condenser coils for fin damage, oil residue, and particulate buildup.
• 4.2 Straighten bent coil fins using an appropriately sized fin comb without puncturing internal copper capillary tubing.
• 4.3 Apply EPA-compliant, non-acidic, foaming coil cleaner to evaporator and condenser coils; allow recommended dwell time and rinse thoroughly with low-pressure water.
• 4.4 Inspect cooling tower basin, fill media, spray nozzles, and drift eliminators (if applicable) for scale, algae, and biological fouling (test and treat for Legionella risk per ASHRAE Guideline 12).
• 4.5 Inspect damper actuators, linkages, and outside air intake louvers for binding, calibration drift, and unobstructed operation.

Phase 5: Electrical & Control System Diagnostics

• 5.1 Inspect all high-voltage and control wiring terminations for thermal discoloration, corrosion, and mechanical tightness (torque terminal screws to engineering specifications).
• 5.2 Test compressor and motor insulation resistance using a megohmmeter (record megohm values; benchmark against historical data).
• 5.3 Measure running load amperage (RLA) and voltage across all phases while equipment is operational; calculate voltage unbalance percentage.
• 5.4 Inspect contactor points, relays, and starters for pitting, welding, or carbon tracking; replace components exhibiting significant wear.
• 5.5 Verify operation of safety controls: high/low pressure cut-outs, oil pressure safety switches, freeze stats, and smoke detectors by manual simulation or electronic testing.
• 5.6 Calibrate thermostat and building automation system (BAS) temperature sensors against a NIST-traceable reference thermometer.

Phase 6: Refrigeration & Combustion Verification

• 6.1 Connect digital manifold gauges to service ports (utilizing low-loss fittings to minimize atmospheric venting).
• 6.2 Record suction pressure, discharge pressure, liquid line temperature, and suction line temperature; calculate superheat and subcooling.
• 6.3 Perform electronic refrigerant leak detection across all joints, valve stems, and service ports.
• 6.4 For gas-fired heating units: inspect burners, flame rollout switches, and heat exchanger surfaces for cracks, corrosion, and proper flame propagation.
• 6.5 Execute a flue gas combustion analysis; record carbon monoxide (CO), oxygen ($O_2$), stack temperature, and combustion efficiency.

Phase 7: Post-Maintenance Verification & Closeout

• 7.1 Remove LOTO devices, re-energize the unit, and perform a dry-run startup sequence.
• 7.2 Verify correct rotational direction of all fans, blowers, and pumps.
• 7.3 Monitor complete operational cycle for a minimum of 20 minutes, verifying stable pressures, temperatures, and amperage draws.
• 7.4 Clean the work site, remove all waste materials, and dispose of old filters, refrigerants, and chemicals in accordance with local environmental regulations.
• 7.5 Update CMMS asset records, attach completed checklist data, close the work order, and report any systemic deficiencies to the Facility Operations Manager.

---

6. Quality Assurance & Verification Criteria

6.1 Operational Tolerances & Benchmarks

6.2 Audit Verification Protocol

• Internal Audit: The Reliability Engineer shall randomly audit a minimum of 10% of completed PM work orders quarterly for data completeness and compliance.
• External Compliance Review: Annual third-party audit of refrigerant usage logs, recovery certifications, and environmental safety records.

---

7. Practical Troubleshooting Scenarios

Scenario A: High Compressor Discharge Pressure & Low Subcooling

• Symptom: Unit trips on high-pressure safety switch intermittently. Condenser approach temperatures are elevated ($> 12^\circ\text{F}$).
• Root Cause: Condenser coil fouling, non-condensible gases in the refrigerant circuit, or restricted condenser fan airflow.
• Immediate Corrective Action Protocol:
  1. Verify LOTO compliance before inspecting condenser coil face.
  2. Perform deep chemical cleaning of condenser coils using approved foaming degreaser and low-pressure water rinse.
  3. Verify condenser fan motor RPM, blade pitch, and rotational direction.
  4. If pressure remains elevated post-cleaning, draw a liquid sample and test for non-condensible gases using a refrigerant analyzer; recover and purge system if contaminated.

Scenario B: Low Evaporator Superheat with Compressor Flooding Risk

• Symptom: Suction line is excessively cold or frosted back to the compressor housing; low compressor superheat ($< 4^\circ\text{F}$).
• Root Cause: Thermal Expansion Valve (TXV) stuck in the wide-open position, bulb loose or improperly insulated, or overcharged refrigerant circuit.
• Immediate Corrective Action Protocol:
  1. Immediately isolate the compressor to prevent liquid slugging and mechanical destruction of internal scroll/piston assemblies.
  2. Check TXV sensing bulb positioning; ensure it is strapped securely at the 4 o'clock or 8 o'clock position on the suction line, cleaned of oxidation, and completely insulated from ambient air.
  3. Verify superheat adjustment setting on the TXV valve stem.
  4. Check system charge via subcooling calculations; recover excess refrigerant if overcharged. Replace TXV if power head has lost its charge.

Scenario C: Unbalanced Phase Current Draw on Three-Phase Blower Motor

• Symptom: Motor runs hot, hums loudly, and trips thermal overload relay. Multimeter reveals phase-to-phase current draw variance $> 10%$.
• Root Cause: Voltage unbalance from the utility source, loose terminal connection, or internal winding degradation (inter-turn short).
• Immediate Corrective Action Protocol:
  1. Execute LOTO procedures.
  2. Inspect line-side and load-side contactor terminals for oxidation, pitting, or loose mechanical fasteners; clean and torque to specification.
  3. Measure incoming line voltages across all three phases ($L_1-L_2$, $L_2-L_3$, $L_1-L_3$); calculate voltage unbalance. If source voltage unbalance exceeds $2%$, notify utility provider.
  4. Disconnect motor leads and perform winding resistance (ohm) and megohm insulation tests. If winding resistance varies by more than $5%$ between phases, condemn and replace the motor.