A critical element of motor servicing technique is being able to determine whether or not a replacement motor that is not an exact duplicate of the original is suitable for the application. As a technician, you must consider a number of factors, but this article focuses on one of the more important issues: nameplate amps.
Bob receives a call from the dispatcher telling him about a restaurant that is having difficulties. When he gets on the roof at the restaurant he notices that the unit's fan motor is turning, but seems to be very slow. As he approaches the condensing unit, the fan stops. With Btu Buddy's help, Bob diagnoses the problem.
When a refrigeration system is designed to maintain a product temperature at or below the freezing temperature of water, there will always be a necessity for the system evaporator to be defrosted at some sort of interval (due to the fact that air may contain large quantities of moisture).
In this issue’s troubleshooting situation, the problem unit we’re facing is a reach-in refrigerator in a restaurant and the customer’s description of the problem is that they discovered spoiled food in the cabinet when they arrived early in the morning prior to opening.
Bob gets a call to go to an office building where its water-cooled chiller is not cooling the building. Bob finds that the suction pressure is a little low and the head pressure is about right but the unit is not cooling the water down to the 45°F design setting. Btu Buddy helps him in going step by step to solve the problem.
When you’re troubleshooting a refrigeration control system, keep in mind that no matter how complicated the schematic might look on paper, the control system is actually only trying to provide a few simple outcomes.
Warmer spring weather is here and Bob is beginning to get calls about units that are not cooling. He has just received a call from an old customer who said that her unit cools fine during the morning and daytime, but at night, it stops cooling. Bob investigates, and with Btu Buddy's help, finds the coil is dirty.
This time around we have a customer who has called to say that it’s warmer than it should be in their home. When you arrive you find a nine-year-old package unit, and you determine in a short time that, electrically, everything is as it should be, which means that what you have is a unit that is running, but is not cooling enough.
The customer had called another contractor and was not pleased with the results, so Bob’s company was called. The other technician said he could not get the compressor to start. With Btu Buddy’s help, Bob checks all the components that have to do with starting the compressor. He finds that the start relay needs to be replaced.
With the approach of 2010, the industry will be faced with a shift in both refrigerants and system lubricants. The impending phaseout of chlorine-based refrigerants mandates that the industry move to lubricants that work satisfactorily with the new hydrofluorocarbon (HFC) refrigerants.
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