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      On-demand appliance repair training videos for Professional Appliantologist members Over 30 hours (and growing!) of original, high quality appliance training webinars developed and given by yours truly are at your fingertips, on topics you won't find anywhere else. Fill in those knowledge gaps, strengthen those areas of uncertainty, and boost your skills. Watch on mobile or desktop at your convenience whenever, wherever.  Ultra Short Primer on Basic Electricity, Circuits, Ohm's Law, and Schematic Reading (Length: 1:04:48) Basic Refrigerator Troubleshooting (Length: 1:10:45) Schematic Reading Workshop, 10/2015 (Length 1:19:08) Troubleshooting Strategies for Computer-Controlled Appliances (Length: 48:34) Semiconductors and PN Junctions (Length: 1:04:37) Appliance Temperature Sensing Devices & Technology (Length: 1:27:33) Voltage Measurements, Meters, Ghost Voltages, and Triac-controlled Neutrals (Length: 1:29:32) Troubleshooting with Tech Sheets, Part 1, 4/2016 (Length: 1:09:26) Troubleshooting with Tech Sheets, Part 2, 4/2016 (Length: 1:21:11) Tech Sheet Review, 4/9/2016: Bosch Speed Cooker, Amana Refrigerator, GE Glass Cooktop Range (Length: 1:22:58) Pulse Width Modulated (PWM) Switches used in Samsung Switched Mode Power Supplies (SMPS) (Length: 27:07) PWM Computer Cooling Fan in a Whirlpool Refrigerator (Length: 14:53) Understanding AC Split-phase Household Power Supplies (Length: 52:41) Troubleshooting a Samsung Electric Dryer without Disassembly using Live Tests and the Schematic (Length: 22:47) Troubleshooting a Bosch Dishwasher No-Heat Problem using the Schematic and Live Tests (Length: 15:38) Linear Motors and Linear Compressors (Length: 55:54) Bi-directional PSC Drive Motor Systems in Whirlpool VM Washers (Length: 56:52) Appliance Service Call Structure and Troubleshooting Strategies (Length: 1:00:16) The Ten Step Troubleshooting Tango and Workshop Exercises (Length: 1:35:39) Troubleshooting Ten-Step Tango Advanced Workshop (Length: 1:32:06) Ten-Step Tango Troubleshooting Workshop: Refrigerators (Length: 1:35:57) Whirlpool Duet Washer Schematic Analysis & Whirlpool Dryer Moisture Sensor System (Length: 1:03:04) Neutral Vs. Ground, Inverter Microwave, Digital Communications, Loading Down in DC loads, and more! (Length: 1:14:45) Gas Oven Service Call After a Parts Changing Monkey (Length: 36:04) AFCI and GFCI Circuit Protection Technology (Length: 41:26) Troubleshooting Samsung Refrigerators and more (Length: 1:29:58) 3-way Valves and Dual Evaporator Refrigerators (Length: 1:15:45) Split-Phase Compressors and PTC Start Devices (Length: 1:11:57) Gas Dryer Ignition Systems (Length: 53:50) Refrigerator Sealed System Thermodynamics, Part 1 (Length: 43:07) Refrigerator Sealed System Thermodynamics, Part 2 (Length 1:09:09) To access these webinars and all the other info-goodies here at Appliantology, become a Professional Appliantologist today. If you need cost-effective, time-flexible, state-of-the-art appliance technical training, check out the Master Samurai Tech Academy.
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printgoon

Knocking from AC carrier 38CKC060300

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printgoon

Hi have a new home home and last year the AC unit would intermittently knock very loudly..it sounds as if it has thrown a rod(if it was a combustion engine). When it has been especially loud only warm air blowns. I have visually inspected it and the fan is turning freely. It may cycle 3 to 15 times between the times it knocks loudly. I have had it serviced every spring, including a week ago, all the techs have been advised of this problem, for which I receive the response.."yeah these units are known for being loud" when I advise that warm air blown during the "loud knocking " times they get a wierd oh crap look. Any ideas, I am in central cal and when its 100 degrees and 6 days out for a repair visit I would rather have a part replaced now. Last summer I had someone watching my home when he heard a loud bang, in which they replaced 2 switched to the toon of $300 bucks. I had the loud knocking before and after the repair. Any ideas?

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jb8103

Intermittent knock? Steady knock, like a rhythm? How long does it last? Is the condensor fan running smoothly during the knocking, or look like it is starting and stopping? Can you observe the behavior of the contactor? Don't do this if you have never been around 230 VAC before.

Short cycle protection delay circuit failure...maybe...?

Only data I can find is for a 50 Hz unit.

Edited by jb8103

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ACtechGUY

You never said how old the unit is. Age of a unit is helpful sometimes. The serial number has the date (week)(month)(year)(example -1 6 98 ) first week of June in 1998 ( in the first 5 or 6 digits) . Units older that 10 years are subject to failures.

What you describe is a major indication that the compressor is failing. Something is coming loose from time to time in the compressor. Sooner or later that something is not gonna go back where it belongs, and then you have no cool - forever.

The KABOOM !!!! noise your housesitter heard was likely a start capacitor (or a KICKSTART) exploding . It can be kinda errrrr......explosive sometimes excl.gif.

The kaboom was unrelated to your knocking problem. It is as simple as the compressor is broken and needs replacing.

SORRY. confused.gif

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jb8103

I suspected it might have been slamming on and off, but a faulty compressor is a much simpler explanation. Occam's Razor.

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