Tripp Lite SRCOOL33K, Service Manual

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9. Basic Test Procedure
9.4 Capacitor
A run capacitor is wired across the auxiliary and main winding of a single-phase permanent split capacitor motor, such as the
compressor and fan motor. A single capacitor can be used for each motor or a dual-rated capacitor can be used for both.
The capacitor’s primary function is to reduce the line current while greatly improving the torque characteristics of a motor. The
capacitor also reduces the line current to the motor by improving the power factor of the load. The line side of the capacitor is
marked with a red dot and is wired to the line side of the circuit
9.4.1 Capacitor Test
1. Remove capacitor from unit.
2. Check for visual damage such as bulges, cracks or leaks.
3. For dual-rated, apply an ohmmeter lead to common (C) terminal and the other probe to the compressor (HERM) terminal.
A satisfactory capacitor will cause a deflection on the pointer, then gradually move back to infinity.
4. Reverse the leads of the probe and momentarily touch the capacitor terminals. The deflection of the pointer should be two
times that of the first check if the capacitor is good.
5. Repeat steps 3 and 4 to check fan motor capacitor.
Note: A shorted capacitor will indicate a low resistance and the pointer will move to the “0” end of the scale and remain there as long as
the probes are connected.
An open capacitor will show no movement of the pointer when placed across the terminals of the capacitor.