Welbilt Koolaire KD0270A, Technician'S Handbook, Page: 97 / 136

Part Number STH047 Rev01 10/18 97
Diagnosing Start Components
If the compressor attempts to start, or hums and trips the
overload protector, check the start components before
replacing the compressor.
CAPACITOR
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.
RELAY
The relay has a set of contacts that connect and disconnect
the start capacitor from the compressor start winding. The
contacts on the relay are normally open. The relay senses
the voltage generated by the start winding and closes
and then opens the contacts as the compressor motor
starts. The contacts remain open until the compressor is
de-energized.