Diagnosing Start Components - Manitowoc S Service Manual

Section 6

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.
Relay Operation Check
1. Disconnect wires from relay terminals.
2. Verify the contacts are closed.
Measure the resistance between terminals 1 and 2.
No continuity indicates open contacts. Replace the
relay.
3. Check the relay coil.
Measure the resistance between terminals 2 and 5.
No resistance indicates an open coil. Replace the
relay.
Part Number 80-1480-3
HARVEST ASSIST AIR COMPRESSOR
Function
The air compressor breaks the vacuum between the
sheet of ice and the evaporator which results in shorter
harvest cycles.
Specifications
115 Volt or 230 Volt - matches the ice machine voltage.
Check Procedure
1. Verify when the air compressor should be running in
the sequence of operation.
2. If the compressor is not running when it should be
check voltage at the control board.
3. If there is no voltage present at the control board,
replace the control board.
4. If there is voltage present at the control board check
for voltage at the air compressor connector.
5. If there is no voltage present at the air compressor
connector replace wire.
6. If there is voltage at the air compressor connector,
use a volt ohm meter to verify there is no continuity
through the motor windings then replace motor.
Electrical System
6-35