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Adventures In Restaurant Maintenance: Refrigeration

In this article I would like to talk about the refrigerators and freezer units commonly found in a commercial kitchen and restaurant. The average unit will give long service with minimal maintenance; however there are a few things you should know that could possibly prevent breakdowns. You should also read Greg’s article on this subject he posted some time back.

The way it works: Any common unit used to cool (refrigerator or freezer) that operates with a refrigerant (freon) works in essentially the same way. I will give you a rough outline so you will get the basic idea.

Every commercial refrigerator or freezer is made up of 3 main parts you can identify:

A refrgeration compressor
1. The compressor: the compressor is really nothing but an electric motor that is sealed (welded) in a metal case. The case will be located on the outside of the unit (not in the compartment to be cooled). Compressors are made by several companies and in various styles but most compressors are made by Copeland. You cannot mistake the compressor for anything else because nothing else on your cooling unit will look like the compressor. Think of the compressor as the HEART of your cooling unit. There is no maintenance that can be done on a welded compressor. It is full of oil but typically the oil is designed to last the life of the compressor.

When a welded compressor goes out all you can do is replace it. A compressor is expensive but it is often cheaper to replace the compressor than to replace the entire unit. I have also replaced compressors because the particular equipment was built into “the line” and it has to repaired rather than replaced.
A Condenser Coil
2. The condenser coil: The condenser coil is square, usually black in color, and will have a fan placed behind it that forces air through it. Most of these coils are around 12 inches by 12 inches. The condenser coil will be located very near the compressor (usually directly in front of it). The fan that forces air through the coil is almost always located between the coil and the compressor. This fan not only removes heat from this coil but has the added benefit of cooling the compressor. You must keep the area where this coil and fan are located FREE FROM ANYTHING that blocks air flow (i.e. don’t stack boxes on top of or in front of the area where the compressor and coil are located). The condenser coil will require cleaning on a regular basis (every 3 months). The coil will pick up whatever is floating in the air in your kitchen and deposit it on the coil.

If you allow the coil to clog up, it will cause your cooling unit not to perform at it’s optimum. In fact if this coil is left completely clogged for any extended period of time it will shorten the life of your compressor or completely burn it up. Think of this coil as one of the LUNGS of your cooling unit. Without air, the HEART (the compressor) will stop.
An evaporator coil

3. The evaporator coil: the evaporator coil is also called the “cold coil”. This coil is located inside the compartment to be refrigerated.  In most cases you will not be able to see this coil without removing a cover. This coil’s purpose is to distribute cold air into the unit. Like the condenser coil, there is a fan near the evaporator coil used to force air through it. The evaporator coil can be many different sizes and is usually a lot thicker than the condenser coil. It is often a silver color (aluminum) and can have several fans blowing air through it. Think of this coil as the other LUNG of your refrigeration unit.

The evaporator coil gets extremely cold when the unit is running. Air on the inside of the refrigeration unit is re-circulated through this coil over and over again and getting colder with each pass. This air is what makes your unit cold. It takes the heat from any object you place in the cooling unit and transfers it to the evaporator coil. The heat is then absorbed by the refrigerant (freon) passing through this coil and delivered to the rest of the system (compressor and condenser coil) to remove it from the unit.

These three main components work in unison to cool your refrigerator or freezer. Your freezer will also be equipped with a defrost heater that melts the frost off the evaporator coil several times a day to keep it from freezing up.

What you as a owner/manager can do:

You can extend the life and efficiency of your refrigerators and freezers by keeping the condenser (outside) coil clean. You can also insure the door gaskets are in good shape and are sealing all the way around. Also train your employees not to leave the door open any longer than necessary.
The refrigerators and freezers are some of the most maintenance free equipment in your kitchen. If you buy a quality unit and see that the minor maintenance described above is done then these units should give you many years of trouble free service.

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  1. Hello Kevin,

    Below is a letter I gave my refrigeration people who are coming out to fix a unit of mine. It is their recomendation to replace the coils and blowers–around $2,000.00. But–I feel something is not right. This is the easy way. I would like to know why–what is broken. One thing you need to know is this unit is a glass door–similar to what you find in 7-11 or small food markets that line the walls for sodas and milk– but iit is much more shallow front to back (36 inches) and when we relocated this unit was converted from a freezer into a refrigerator- and gave me trouble free service for the first 18 months at our new location. It is the last nine months that we have encountered the same sporadic problem.


    The idea of spending a few thousand is something we would rather not due at this point in time. Before replacing the coils and blowers – -can you make any sense of what is taking place here. I have outlined all I know and have seen below. Maybe its just one part or mechanism that is a lemon. Its not a leak, there is no refrigerant being lost. The blowers work. Please read below.

    This glass door unit goes down once – -sometimes twice a month, When it goes down it blows hot air for multiple hours. What we cannot tell, what we are not 100 percent sure of is, if it will begin to blow cold air on its own – – or if our turning it off, somehow effects it. I DO NOT THINK IT WILL BLOW COLD AIR ON ITS OWN IF LEFT RUNNING — BUT AM NOT SURE. In this last case I came into the store this past Saturday morning at 6:00 AM it was blowing hot air. It began blowing hot air sometime Friday night SINCE ITEMS WERE REMOVED FROM IT AND STORED ELSEWHERE. I turned off the switch on the side of the box at 6:30 AM Saturday morning. I think we turned it back on at Saturday noon and checked it a few hours later and it was still hot air – – I am not sure of this – – Josh would remember this. I turned the switch back on at 4:00 PM Sunday (30 hours later) . At first it felt like hot air was blowing, but when I checked the unit at 10:30 PM (36 hours from incident) Sunday evening it was cold again.

    1.) I assume it is NOT the timer for defrost since it only happens once to twice a month. A timer would make it happen within a twenty four hour cycle and many times during the week.
    2.) It is possible that the door is being left open, it raises the temperature inside this box and causes something to happen. If yes – -why sometimes yes and sometimes no – -because the door can be left open, raises the temperature and nothing happens as well. I mention this because I recall doing a Sunday Inventory in this case – -having the door open for a prolonged period of time – -and this occurred – -it went warm and we needed to move everything out. I never knew if was coincidence or not.
    3.) Does it have anything to do with outside temperature. If yes – – we have had previous hot days in the last few weeks and it continued to work. Why only sometimes.
    4.) I guesstimate that there is something – -an expansion valve or some type of mechanism that is getting periodically stuck. This is the only thing that makes sense. It is periodic. It can work for two months straight – -and then begin to blow hot air. This time we waited instead of getting immediate service. After 30 hours – – I turned on the switch and five hours later its cold.
    5.) Why would the conversion from freezer to refrigerator cause this. If it did – -why after a year of working fine.
    6.) Could there be one part – -a motor, a valve, something – – that is a lemon and goes funky once in a while – -but comes back and operates the way it should the rest of the time. Not broken – – just a lemon.

    Ca you help me Kevin

    Thank you

    Michael Maggio

  2. Hello Michael,

    I believe your problem is the unit is going into defrost (the defrost heater is kicking on). You said “this unit was converted from a freezer into a refrigerator” ; when you do that (and I have done it several times), you have to completely disable the heater that defrosted the coil when it was a freezer. I would remove it all together. Then you have to rewire the part of the unit that makes the compressor go off when it is in defrost.

    Your refrigeration guy don’t think it is going into defrost because it is only happening twice a month (that he knows of). The fact is you need to leave a data logger on this unit for a week and see if there is a temp drop every 24 hour period; I would hazard a guess it is happening more than you know (could even be at night).

    I would not spend $2000 on coils before I found out what is making the unit do this. To do that you need to insure it is wired right and the defrost heater is disabled or completely removed. The element might not be coming on at all but the compressor could be shutting down.

    I hope this helps you Michael,

    Kevin Loving

  3. Kevin, I have a seasonal (summer) Lodge that we only have open 3 months out of the year. Do you know if it is a bad thing to turn off all the electricity and heat during the winter. Will this be a detriment to my refrigeration units. Last year I kept the heating at 55 all winter but it was terribly expensive. do not want my 3 year old units to get ruinned but I am looking at the bottom line.

    thank you

    • Hi Margie,

      Kevin isn’t able to answer your questions at this time, but I did discuss your questions with another certified service tech and here’s what we came up with:

      Unplug your refrigeration units for the winter and make sure any water lines are completely drained and disconnected. They should weather the cold just fine like that. Let me know if you have any other questions!

  4. I have a commercial refrigerator that I am not currently using, but need an additional freezer. Is it possible to convert the refrigerator to freezer and if so, what is the estimated cost?

  5. Marti you can consult for this refrigerator to freezer by any HVAC consultant. If you want to avail commercial refrigerator repair in NJ So:
    They are the best.

  6. Hey guys,

    I have a small fridge for beverages in my gym. It keeps freezing random drinks. It is on the lowest setting possible. It seems like the fan at the bottom is not turning off. I have it at a spot where the sun sometimes hits it. I don’t know if that is a problem, or it is simply the fan that is the issue. Any ideas/help would be great!



  7. Move the fridge out of the sun,a small fridge does not have a very good r-factor and the sun is more than likely keeping it just above the cut out temp inside which would be aprox 38 degrees far. if turned down to lowest setting,try this if not replace thermostat i fridge!

  8. Since you are preparing to make a significant investment in the long run, you might want to think about buying an extended warranty. just my thoughts.

  9. Nice Blog and Great Post.. thanks For Share this Blog…

  10. My brother has a restaurant and he has people who take care of the refrigerators because the refrigerators are very very important if you run a restaurant. I think that he will like this article and I will send it to him. Thanks for sharing!

  11. can I swap compressors from 1 fridge to another. both are 60″

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