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Top Maintenance Mistakes to Avoid: Ensuring Optimal HVAC Performance

Routine preventative maintenance is necessary for providing continued efficient and reliable operation of equipment. Just like car maintenance—where skipping oil changes, ignoring tire pressure, or neglecting brake inspections can lead to costly repairs—HVAC systems require consistent care to operate properly.

Improper installation, adjustment, alteration, service, or maintenance can lead to property damage, personal injury, or loss of life.

Common Pitfalls That Lead to Costly Issues

A failure to follow proper maintenance procedures can result in the premature failure of your system and may potentially void the unit's warranty. Many operational problems stem from neglecting routine maintenance checks, such as monitoring airflow, changing filters, and maintaining refrigerant charge.

Top Maintenance Mistakes to Avoid

Ignoring Filter Changes

Do not operate the unit without filters in place. Operation of the equipment without filters could result in a clogged evaporator coil. It is strongly recommended to replace the filter media monthly to maintain optimum unit efficiency. Filters should also be checked a few days after initial startup, as dust and debris from construction may cause premature loading.

Skipping Seasonal Tune-Ups

At least once each year, a trained, qualified service technician must inspect the unit. Periodic routine maintenance checks are necessary during operation, which includes things such as checking airflow, filters, condenser water flow, and refrigerant charge.

Neglecting Coil Cleaning

Indoor cooling/evaporator coils must be cleaned regularly (at least annually) by an HVAC professional to maintain unit efficiency and operation. Dirty evaporator coils may eventually freeze up. Condenser coils must be inspected annually to ensure airflow is unrestricted and should be cleaned at a minimum of once a year.

  • Warning on Chemicals: Using improper cleaning techniques or incorrect chemicals could result in coil damage, system performance fall-off, and potential leaks requiring coil replacement. Consult the unit's Installation Operation and Maintenance (IOM) manual for proper coil cleaning practices.

Failing to Check Refrigerant Levels

Routine service checks must include reading and recording suction pressures and checking for normal liquid sub-cooling and evaporator superheat. Adjusting the charge in the field must be determined based on these values.

Service History Documentation

The IOM manual contains a Maintenance Log that must be kept with the unit. It is the responsibility of the owner and/or maintenance/service contractor to document any service, repair, or adjustments.

Using Unqualified Technicians

Improper installation, adjustment, alteration, service, or maintenance can cause property damage, personal injury, or loss of life. Startup and service must be performed by a qualified service technician.

Consequences of Maintenance Mistakes

Reduced Efficiency

Failure to maintain the system can result in clogged evaporator coils, leading to reduced heat transfer across the coil and liquid being returned to the compressor. This can damage the compressor and reduce oil return, which is essential to lubricate the compressor components.

Shortened Equipment Lifespan

Poor lubrication due to liquid oil/refrigerant pumping seriously shortens compressor life. Other critical errors that shorten lifespan and risk voiding the warranty include:

  • Improper Compressor Cycling: Compressors must follow appropriate on/off cycling guidelines to prevent overheating and maintain proper oil level. 

  • Incorrect Rotation: Scroll compressors are directional, and their rotation must be checked by a qualified technician at startup. Operating a scroll compressor in the wrong direction will damage it. 

  • Voltage Imbalance: Voltage imbalance will cause motor overheating and premature failure. 

  • Freezing: Failure to properly drain and vent coils when they are not in use during freezing temperatures may result in coil and equipment damage. 

 

Best Practices

Adopting proactive best practices ensures longevity and optimal performance of AAON equipment.

  • Monthly Inspections: Inspect supply fans, evaporator coils, and air filters monthly.

  • Annual Checks: A qualified service technician must perform a check-out at least once a year.

  • Energy Recovery Wheel Cleaning: Cleaning frequency depends on air quality class.

Always refer to the manufacturer’s Installation, Operation, and Maintenance (IOM) manual for equipment-specific instructions and recommended procedures.