Ice Breaker: Diagnosing Failures in Refrigeration
Determining Why a Refrigeration System Is Not Operating Properly
Determining why a refrigeration system is not operating properly is not normally a difficult task. In fact, many times, identifying a system’s issue is quite easy. However, there are some system problems that can be tricky and difficult to identify, but they are typically the exception. A high percentage of the time, a technician can easily
determine the cause of a system failure. The actual repair might not be so easy, but again, determining what needs to be done is generally not a problem.
Sometimes we over think both the easy and hard problems, making a true system issue more difficult than it really needs to be. When faced with a problem you cannot easily identify, it helps to ask, “What’s changed?” If the system was previously working, what’s changed to cause it to malfunction? Look around, think outside the box, speak to the owner and/or operators, and look for what has changed. This can help you to find and identify the root cause of the system problem.
Here’s an example of how this can help. You are called out to service an open display meat cooler in which the case temperature is higher than normal. You check the entire refrigeration system and cannot find the problem. So you ask yourself, “What’s changed?” You look around, speak to the department manager, and after some investigation, discover that following some recent mechanical work, a new HVAC diffuser was placed close to the display case. You then discover the discharge air from the diffuser is disrupting the air curtain of the display case. You temporarily cap off the diffuser and the case temperature comes down within design specifications. You then notify the department manager to have the HVAC contractor return and relocate the diffuser.
While servicing a walk-in freezer, you’re told the evaporator freezes up about every week or two. You check the defrost system and it seems alright. You check the refrigerant charge and it also seems OK. So again you ask yourself, “What’s changed?” Once again, you look around, speak with the owner, and discover that the walk-in freezer was originally used more as a storage case, but, now that business has increased, the case is used more for short-term storage with frequent door openings. You also learn that the door is being held open for longer periods than during previous use. Examining the defrost system, you see the defrost time clock has only one defrost scheduled every 24 hours, which might have been okay when the case was used for long-term storage, but now with the increase in door openings and increase in the amount of time the door is held open, additional defrost cycles may be needed. So, you add an additional defrost period, and it seems to solve the problem.
Remember, when faced with a problem that is not readily identified, ask yourself, “What’s changed?” Look around, think outside the box, and speak with the owner/operator of the equipment. These all can help identify the problem.
Publication date: 12/2/2013