Manitowoc FLAKE/CHIPLET QC0700 Service Manual page 120

Electrical System
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 closed
(start capacitor in series with the start winding). The
relay senses the voltage generated by the start winding
and opens the contacts as the compressor motor starts.
The contacts remain open until the compressor is de-
energized.
Disconnect electrical power to the condensing unit
before proceeding.
Relay Operation Check
1. Disconnect wires from relay terminals.
2. Verify the contacts are closed by checking for
continuity between terminals:
QF400 QC700/QF800
10 & 11
No continuity indicates open contacts. Replace the
relay.
6-58
!
Warning
RFC2085/
RFC2385
(QF2200/QF2300)
1 & 2 1 & 2
3. Check the relay coil. Measure the resistance
between terminals:
QF400
10 & 11
No resistance indicates an open coil. Replace the
relay.
4. Replace control box cover and restore electrical
power to the ice machine.
Replace control box cover before proceeding.
5. Move toggle switch to the ICE position.
6. The compressor start winding should energize for
less than 1 second. Continued high amperage draw
could indicate:
• Low incoming power supply (Check voltage at
compressor start-up when load is greatest)
• Defective relay
• Defective capacitor
• Defective compressor
• Verify voltage and replace all start components.
7. If all of the previous tests are satisfactory and the
compressor will not operate or continue to operate,
replace the compressor.
Revised 8/2003
Section 6
RFC2085/
RFC2385
QC700/QF800
(QF2200/QF2300)
1 & 2 1 & 2
!
Warning
Part No. 80-1214-3