Manitowoc RNS012, Technician'S Handbook

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88 Part Number STH044 10/13
Compressor Drawing Locked Rotor
To determine if the compressor is seized, check the
amp draw while the compressor is trying to start.
The two likely causes of this are a defective starting
component and a mechanically seized compressor.
To determine which you have:
1. Install gauge on high and low side.
2. Try to start the compressor.
3. Watch the pressures closely.
A. If the pressures do not move, the compressor
is seized. Replace the compressor.
B. If the pressures move, the compressor is
turning slowly and is not seized. Check the
capacitors and relay.
COMPRESSOR DRAWING HIGH AMPS
The continuous amperage draw on start-up should not
be near the maximum fuse size indicated on the serial
tag.
Diagnosing Capacitors
• If the compressor attempts to start, or hums and
trips the overload protector, check the starting
components before replacing the compressor.
• Visual evidence of capacitor failure can include a
bulged terminal end or a ruptured membrane. Do
not assume a capacitor is good if no visual
evidence is present.
• A good test is to install a known good substitute
capacitor.
• Use a capacitor tester when checking a suspect
capacitor. Clip the bleed resistor off the capacitor
terminals before testing.