The human factor - Improving maintenance of HVAC&R systems: a human error perspective

By Mfundo Nkosi

The aim of this article is to identify the possible human errors in the maintenance of HVAC&R systems. An understanding of human errors and their causal factors can assist in the reduction of maintenance failures.

Maintenance can be viewed as a process of keeping or returning a piece of equipment to an operable condition. Now, maintenance tasks in refrigeration and air-conditioning systems should enable the systems to function at adequate levels of reliability and operability at reasonable costs.

During operation, the acceptable level of reliability of refrigeration and air-conditioning systems depends on the high-quality performance of the system’s technical components and personnel working on it.

Based on many studies in human factor engineering, it can be approximated that equipment failures due to human error are about 80%, as opposed to technical failures.

Since the beginning of engineering, the engineering practitioners have focused their efforts on improving the technical components of a system, with less attention being paid to the humans working on it.

Human error

It is a known fact that nothing built by humans can operate issue-free until the end of its specified lifetime. However, adopting good maintenance practices can assist in improving the reliability and useful life of a system. Maintenance can be defined as those activities required to keep a facility in as-built condition and, therefore, continuing to have its original productive capacity. A higher standard of maintenance is dependent on the reliability of maintenance personnel. Therefore, there is a serious need to look at the impact of the human element when addressing issues pertaining to refrigeration and air-conditioning systems. Dhillon and Liu (2006) states that “human error in maintenance is a subject which in the past has not been given the amount of attention that it deserves.”

The questions that need to be asked to regard human error as a serious subject of scientific enquiry are as follows:

  • Who designs a system?
  • Who manufacturers a system?
  • Who installs a system?
  • Who operates a system? If it is operated through automation, then who programs a system?
  • Who maintains a system?

For sure, the answer to all the above questions is ‘humans’; therefore, the importance of analysing the impact of human errors in engineering systems is justified.

According to this study, “human error may be defined as the failure to perform a specified task (or the performance of a forbidden action) that could lead to disruption of scheduled operations or result in damage to property and equipment.” Based on many studies in human factor engineering, it can be approximated that equipment failures due to human error are about 80%, as opposed to technical failures. Figure 1, which was extracted from EFCOG (2007), presents the statistics of occurrence and contribution of human errors in engineering systems failure.

Mfundo Nkosi Graph MMFigure 1: Why the human performance approach? (Adapted from EFCOG, 2007.)

The figure is an indication that more attention paid to equipment has significantly contributed to the decrease in failures due to technical causations, but leaves human error at a higher level.

Human error categorisation

Various errors can be committed at different stages of a system. Human errors are categorised in terms of the stages where they occur. The following are some of the categories of errors that can be committed in a system:

  • Design errors;
  • Manufacturing errors;
  • Installation errors;
  • Operation errors; and
  • Maintenance errors.

It is apparent that the maintenance personnel should be very careful when addressing equipment failures, since some of the active failures during operation might be due to latent failures inherited by the system from previous phases.

There are various causes of human error, such as insufficient skills of technicians, inadequate work design, poor communication, working under pressure, incorrect tools, and complicated and/or badly written operation and maintenance manuals. It can be noted that the refrigeration and air-conditioning technicians can also be exposed to these kinds of conditions, and when combined with human inherent erring characteristics, errors can then happen, leading to negative impact on the system. It is essential for managers and technicians to understand the effect of their actions in performing substandard maintenance, which can frustrate their clients and lead to loss of business in the case of contracted work.

Type of human errors

This section looks at the type of human errors that can be committed during maintenance and in other phases of a system.

Slips and lapses: are due to distractions and loss of concentration. These are called slips of action and lapses of memory. In this case, the maintenance technician was knowledgeable of his or her task, but made an error in actions or missed a small detail. As an example, a maintenance technician, after fixing a leak, charges the system with an incorrect amount of refrigerant. The contributing factors to these errors might include time pressure and badly written procedures. Therefore, through raising awareness about human error and creating clear checklists, these errors can be minimised.

Human error is a serious issue, which needs to be properly addressed in refrigeration and air-conditioning systems.

Mistakes: to do something wrong believing it to be right, decision-making failures, and poor judgement. As an example, a maintenance technician undercharges the refrigerant into the system because he or she has not fully grasped the procedure. This type of error can be addressed through training.

Violations: are categorised as intentional failures and are complicated to deal with. Various factors are responsible for this type of error, especially when there is a perceived advantage of violation. To illustrate, a maintenance technician working at a height that is above the legal limit, spotted not wearing a safety harness. The perceived benefit by a technician might be to move freely around the system without a harness, but not bearing in mind that his or her life and the equipment are at risk in the event of a fall. Lack of proper supervision and reporting systems can also be the cause of this type of error. This type of error can be addressed through routine monitoring, improving supervision, and expressing the importance of rules and procedures to technicians.

Latent organisation failures: are due to organisational culture, supervision, and decisions made by management. Also, maintenance technicians commit errors due to lack of support from the organisation’s management. Other problems are attributed to lack of structures and initiatives by management to establish an enabling environment for their technicians.

Problems encountered in HVAC&R systems

Various problems are encountered by refrigeration and air-conditioning systems during operation, but through maintenance they can be fixed. Table 1 presents the refrigeration and air-conditioning system problems, together with the impact they have on the system and on users.

HVAC&R problems Impact of the problems
  • Improper design
  • Low airflow
  • Faulty installation
  • Refrigerants leaks
  • Insufficient maintenance
  • Harm personal comfort
  • Undercharged refrigerant
  • Adverse energy bills
  • Overcharging the refrigerant
  • Degradation of the quality of air
  • Poor service procedures
  • Accumulation of existing problems
  • Unqualified service technicians.
  • Disturb performance and efficiency of the system
  • Threaten the health of the users
  • Harm to the environment.

Table 1: HVAC&R systems problems

One could note that all the problems of refrigeration and air-conditioning systems stated in Table 1 are attributable to human error. Hence, the maintenance organisations should ensure that their teams are highly motivated and equipped to perform their duties. According to Mason (n.d.), a maintenance technician “who is motivated, well trained, under no time pressure, given the correct information, and working with equipment which has been designed to be maintenance friendly, will likely complete all specified maintenance work to a high standard.”

It is further stated that “however, the more these requirements are not met, the less likely it becomes that the maintenance work will receive the desired attention and shortcuts in work methods become increasingly probable, and direct damage to the plant.”

Various programmes and models are available to assist in addressing human error. The author has developed a human factor framework that has the potential to identify and solve human error in various industries, including refrigeration and the air-conditioning industry.


It can be concluded that human error is a serious issue, which needs to be properly addressed in refrigeration and air-conditioning systems. Various problems are encountered in HVAC&R systems that can be directly linked to human error. These errors can be reduced or eliminated through raising awareness on human errors, improving supervision, and providing training.


  1. Dhillon, B., and Liu, Y. (2006). Human Error in Maintenance: a review. Journal of Quality in Maintenance Engineering , Vol. 12 (No. 1).
  2. EFCOG. (2007). Human Performance Improvement and Feedback & Improvement, Cause Analysis Workshop, Available from:  
  3. US Energy Department. (n.d.)
  4. Mason, S. (n.d.). Improving Maintenance by Reducing Human Error, Health Safety & Engineering Consultants.


RACA Readers promo 01


IMD logo Whitesmall

Interact Media Defined (IMD), is one of South Africa’s leading multi-media magazine publishers READ MORE


Cookie policy
Privacy & Cookie policy
Privacy policy

Talk to us

JHB T : +27 (0) 11 579 4940
CPT T : 0861 727 663
E :

13A Riley Road, Bedfordview,
South Africa 2007

© Interact Media Defined