Refrigerator Troubleshooting Diagram

Semi-Hermetic Compressors Field Repairs

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Semi-hermetic compressors are frequently used on light commercial air conditioning and refrigeration equipment. With the cast iron body and bolted head, oil pan, oil pump, and end cover that opens the electric motor section for service, certain field repairs can be made. Only two types of repairs should be attempted in the field. Replacement of valve plate assembly and/or the oil pump, if the unit has separate pump. No other type of repair should be attempted in the field.

The semi-hermetic compressor has many of the same component parts as an automobile. To rebuild a compressor thoroughly, special tools and test instruments are needed. If a compressor is not pumping properly, the head bolts and head should be removed carefully from the block. Looking into the cylinders, you can turn the crankshaft and see if all of the pistons move up and down. If there is a broken piston or connecting rod, put the head back on and replace the whole compressor. Some say that a compressor with the above condition would make a lot of noise. In some cases, this is so; however, I’ve come across many compressors that had broken rods or pistons and didn’t make any noise.

If the pistons are alright, examine the valve seats and the valve reeds. Also, examine the head gaskets. There is one gasket between the block and the valve plate and another gasket between the valve.

Written by sam

November 10th, 2019 at 8:23 am

One Response to 'Semi-Hermetic Compressors Field Repairs'

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  1. Hello Gents
    Good day for you and I hope you okay
    I need someone to advice for technical problem we have in our Freezer unit
    We have Walk In freezer unit have one Evaporator unit
    This one we can run condensing unit 1 or condensing unit 2 as per schematic diagram below , when we run condensing unit 1 we open Valves 1 for Low and High pressure and close Valves 2 for condensing unit 2
    I need to know what the sequence should be follow when swaps between the condensing two units feed one evaporator unit
    We have many problems after we install the condensing units from 2 years ago specially in compressor
    One compressor stuck the pistons and draw much load current
    And other comp not pumping good
    Many Thanks and your fast replay are highly appreciated

    Hossam hassan

    10 Apr 17 at 11:06 am

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