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OT: I need a refrigeration expert!

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  • OT: I need a refrigeration expert!

    We have two walk-in refrigeraters. They share a compressor that is located in the basement. The units inside the actual refrigeraters seem to be working. The compressor is not kicking on. Of course this has happened on a Sunday afternoon and we haven't been able to locate a repairman that will come out today.

    Is there anything I can look at on the compressor that will give me a hint as to what might be wrong?
    Location: The Black Forest in Germany

    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

  • #2
    Something I've dealt with on our temp chambers is the high pressure overlimit. There are usually two buttons on a box attached to the compressor. One is the high pressure limit, and I don't remember what the other one is. You just push the button to reset.

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    • #3
      Originally posted by Forestgnome View Post
      Something I've dealt with on our temp chambers is the high pressure overlimit. There are usually two buttons on a box attached to the compressor. One is the high pressure limit, and I don't remember what the other one is. You just push the button to reset.
      So far I haven't found any reset buttons. I took the cover off the pressure switch to see if the contacts had arc'd shut or open but all looked ok.
      Location: The Black Forest in Germany

      How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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      • #4
        Did you check to see if power was getting applied to the compressor drive motor?

        If so, then motor problem is likely.

        If not, then trace back to see where power is not getting through, ad fix that. Might be a safety switch of some type, in which case one needs to find out if there really is a problem with whatever is being monitored.
        CNC machines only go through the motions

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        • #5
          Same thing happened on the HVAC unit for my house. LSS, ants found their way into the compressor start contactor, and between the contacts. When the relay closed, the ants were fried and their remains prevented current flow. Cleaning the contacts cured the problem.
          “I know lots of people who are educated far beyond their intelligence”

          Lewis Grizzard

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          • #6
            Is the compressor hot? They are usually thermally protected.

            Is the fan on the condenser running? It normally is wired in parallel with the compressor power. Fan running or not will give troubleshooting hints.

            A fairly common failure is the start capacitor if it uses one. Of course, checking for power as Jerry mentioned is the first check.

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            • #7
              Besides what Dave posted, is the circuit breaker or fuses good to the compressor unit? Is the compressor or condensing unit fans on? If its low or out of refrigerant the low pressure switch might be open, or if its water cooled there could be a high pressure limit switch, and its resettable.

              I only have 23 years experience in commercial refrigeration and HVAC so I am sure some experts will chime in.
              Retired - Journeyman Refrigeration Pipefitter - Master Electrician

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              • #8
                Originally posted by wmgeorge View Post
                I only have 23 years experience in commercial refrigeration and HVAC so I am sure some experts will chime in.
                No need to apologize.

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                • #9
                  Originally posted by Sparky_NY View Post
                  No need to apologize.
                  Yes I thought the same! Everyone has to start somewhere!

                  Yes the fans are running on the condensors that are located inside the refrigeraters.

                  For today they moved all the food to other refrig. in the house. They even took over my refrig. in my office bar!
                  Location: The Black Forest in Germany

                  How to become a millionaire: Start out with 10 million and take up machining as a hobby!

                  Comment


                  • #10
                    Originally posted by Black Forest View Post
                    Yes I thought the same! Everyone has to start somewhere!

                    Yes the fans are running on the condensors that are located inside the refrigeraters.

                    For today they moved all the food to other refrig. in the house. They even took over my refrig. in my office bar!
                    The fans inside the refrigerators are on the evaporator coils, the condenser fan is located on the coils at the compressor. (unless it is water cooled) See if that fan is running.
                    Feel the compressor, its temperature gives a lot of hints to possible causes. These are a couple of the first things I check before ever picking up a tool.

                    (I started in the early 70's, master electrician since 1982 so I am slowly learning)

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                    • #11
                      What Sparky said, and the Evaporator (cooling coil) fans are running all the time on a commercial WI Cooler the power is Independent of the power to the Condensing unit in the basement. Once you understand that, you can begin to troubleshoot as suggested.

                      You may or may not have a defrost timer that shuts the compressor (condensing) unit down and the air over the Evaporator defrosts the coil. We hardly ever needed defrost timers, but this is in Germany.
                      Retired - Journeyman Refrigeration Pipefitter - Master Electrician

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                      • #12
                        Originally posted by Sparky_NY View Post
                        The fans inside the refrigerators are on the evaporator coils, the condenser fan is located on the coils at the compressor. (unless it is water cooled) See if that fan is running.
                        Feel the compressor, its temperature gives a lot of hints to possible causes. These are a couple of the first things I check before ever picking up a tool.

                        (I started in the early 70's, master electrician since 1982 so I am slowly learning)
                        No the fan doesn't run on the condenser at the compressor. Everything is moved so I won't spend anymore time on this. Tomorrow the firm will come that installed the units. Thanks for the help.
                        Location: The Black Forest in Germany

                        How to become a millionaire: Start out with 10 million and take up machining as a hobby!

                        Comment


                        • #13
                          Originally posted by Black Forest View Post
                          No the fan doesn't run on the condenser at the compressor. Everything is moved so I won't spend anymore time on this. Tomorrow the firm will come that installed the units. Thanks for the help.
                          Good luck. Personally, I don't like the idea of a single compressor/condensing unit serving two walk ins. With both walk ins out of service you see one of the main reasons

                          Hopfully this won't dip too deep in to your hobby budget..

                          Comment


                          • #14
                            Originally posted by Sparky_NY View Post
                            Good luck. Personally, I don't like the idea of a single compressor/condensing unit serving two walk ins. With both walk ins out of service you see one of the main reasons

                            Hopfully this won't dip too deep in to your hobby budget..
                            I am not worried about what the repair on the unit will cost. What I am worried about is the horse my wife and daughter are dragging me off to see tomorow......that could get real expensive!
                            Location: The Black Forest in Germany

                            How to become a millionaire: Start out with 10 million and take up machining as a hobby!

                            Comment


                            • #15
                              Originally posted by Sparky_NY View Post
                              Good luck. Personally, I don't like the idea of a single compressor/condensing unit serving two walk ins. With both walk ins out of service you see one of the main reasons

                              Hopfully this won't dip too deep in to your hobby budget..

                              It too bad we could never get him to check the circuit breakers for the condensing unit, a lot of time its either tripped or someone forgot they turned it off! In supermarket refrigeration work, we often had a lot of cases or reach ins on one rack.
                              Retired - Journeyman Refrigeration Pipefitter - Master Electrician

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