Sealed Refrigeration System Repairs - Sinclair AMC-15A Service Manual

If test shows:
A. Below normal high side pressure.
B. Above normal low side pressure.
C. Low temperature difference across coil.
The compressor valves are faulty - replace the compressor.
11.1.4 Terminal overload (external)
Some compressors are equipped with an external overload which is located in the compressor
terminal box adjacent to the compressor body The overload is wired in series with the common
motor terminal. The overload senses both major amperage and compressor temperature. High
motor temperature or amperage heats the disc causing it to open and break the circuit to the
common motor terminal.
Heat generated within the compressor shell is usually due to:
1. High amperage.
2. Low refrigerant charge.
3. Frequent recycling.
4. Dirty condenser.
11.1.5 Terminal overload (internal)
Some model compressors are equipped with an internal overload. The overload is embedded in the
motor windings to sense the winding temperature and/or current draw. The overload is connected in
series with the common motor terminal.
Should the internal temperature and/or current draw become excessive; the contacts in the overload
will open, turning off the compressor? The overload will automatically reset, but may require
several hours before the heat is dissipated.
11.1.6 Checking the internal overload
1. With no power to unit, remove the leads from the compressor terminals.
2. Using an ohmmeter, test continuity between terminals C-S and C-R. If not continuous, the
compressor overload is open and the compressor must be replaced.
11.2

Sealed refrigeration system repairs

11.2.1 Equipment require
1. Voltmeter
2. Ammeter
3. Ohmmeter
4. E.P.A. Approved Refrigerant Recovery System.
21
Basic test procedure