Author Topic: Summer Refrigeration Failures  (Read 1490 times)

Offline TechnicianBrian

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Summer Refrigeration Failures
« on: July 12, 2008, 06:44:38 AM »
Summer has arrived (at least in the northern hemisphere) and refrigeration service calls are on the rise as we enter one of our industries peak seasons for work. But before you go condemning a unit or cutting into the system on one of these calls, take a moment and think about the refrigeration process.



Keeping Cool
With the heat of summer, our trusty refrigerators and freezers are constantly asked to work harder to accomplish the same level of heat transfer simply because of the environment the unit is now working in. The first law of thermodynamics tells us that heat moves from a warmer place to a cooler place. And as long as there is a differential in temperatures between the heat we are trying to remove, and the place we are trying to move the heat to, we should have refrigeration. But consider the refrigerator sitting in the garage, or the closed up house on a very warm summer day. As the ambient temperature of the room begins approaching the temperature of our units condensing system, the amount of heat that can effectively transfer decreases so the system components must work harder and more often to meet the same level of cooling demand. And it is this demand that is usually behind the high number of failures that we see this time of the year.

Looking for Simple Answers
Often we are hoping to find the simple fix to help the customer and get on to the next call, but as technicians, we find ourselves looking for the more difficult (and less likely) problems because our minds will skip over what we consider to be routine or basic in nature (such as tearing into a dryer only to find the breaker had been tripped). And when it comes to summer and refrigeration service, our minds wander off to burnt up compressors, restricted dryers, or even the occasional hole in the evaporator, but we need to stop and realize that the systems still work just like they did in the middle of winter, it's just our current environment has created efficiency problems and those are the items we need to deal with.

Case in Point
What is the most likely reason for a refrigerator or freezer to be poorly cooling on a warm summer day? I hope everyone is thinking dirty condenser, condenser airflow problem, broken condenser fan, or most anything else that prevents proper airflow across the condenser coils. Everyone of us is aware of the problem a dirty or blocked condenser will create, but for 9 months out of the year (short summers in Oregon) the air inlet grill covered in matted cat hair, random bits of debris and dust, or even a plastic grocery bag or two doesn't bring about a noticeable problem to our customers. They can tell its cooling and it still makes ice, but they never notice it's running 90% of the time to do it. So we need to step back and look at how the system works and the environment it is located in to ensure we are covering our basics prior to jumping into the unit and looking for a problem that may not exist.

Fixing the Symptom
Sure components break, probably more so during the summer months, but I wonder how many compressor start devices are replaced only to fail a short time later. Or how many ice maker modules (or entire ice makers for that matter) seem to have fixed the problem for now, only to become a reoccurring service issue all summer long. If we find a problem, we need to make sure we are fixing the problem and not just the symptom. By looking a bit deeper into a component failure, or unexplained cooling problem, we can feel confident in our diagnosis and repair. Below I have included some of the issues I know get missed when we are fixing the symptom.
  1. Clean the condenser coils and fan if you do nothing else. The systems ability to effectively transfer heat away from the condensing system will cause a cooling or cooling related issue 100% of the time whether the customer sees a problem or not.
  2. Instruct the customer on airflow issues and how a little maintenance can prevent bigger problems. Use a car radiator analogy to explain how the refrigeration system works because they will understand what happens when the cars fan belt breaks. From blocked air inlet and exhaust grills, to inadequate spacing to the wall, or my personal favorite, the refrigerator in the uninsulated shed, are all environmental (customer related) conditions that will cause problems.
  3. Check the compressor with your meter before installing a new start kit. This may be the correct solution, but why did the last one fail? Make sure you have the appropriate resistance between the terminals and no continuity to the housing. Use your amp clamp to verify the current draw during start up and running is within expected limits. An overheated or partially shorted compressor winding could place an added load on the starter.
  4. Before you replace an ice maker or it's module, make sure the freezer is cold enough. If you use 15 degrees F as a good rule of thumb, remember that no ice will be made until that thermostat in the ice maker has reached this magic temperature. Freezer sections that are poorly cooling may not be able to maintain a cold enough temperature to keep making ice and the result may be it makes ice overnight, but off and on during the day (see item #1 for possible solution).


Summer and broken refrigerators go hand in hand and probably always will. As technicians, we sometimes forget that we are here to solve problems and not just fix them for the customer. By paying more attention to the units we are working on and remembering to check the basics, maybe one of these years our call loads will allow us to take our vacation during the summer.



 

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