Manitowoc QR0320A Service Manual page 99

Section 6
There are other problems that may cause compressor
start-up failure with a good PTCR in a new, properly
wired ice machine.
• The voltage at the compressor during start-up is too
low.
Manitowoc ice machines are rated at ±10% of
nameplate voltage at compressor start-up. (Ex: An
ice machine rated at 208-230 should have a
compressor start-up voltage between 187 and 253
volts.)
• The compressor discharge and suction pressures
are not matched closely enough or equalized.
These two pressures must be somewhat equalized
before attempting to start the compressor. The
harvest valve (and HPR valve on remotes) energizes
for 45 seconds before the compressor starts, and
remains on 5 seconds after the compressor starts.
Make sure this is occurring and the harvest valve
(and HPR solenoid) coil is functional before
assuming that the PTCR is bad.
CHECKING THE PTCR
Disconnect electrical power to the entire ice
machine at the building electrical disconnect box
before proceeding.
1. Visually inspect the PTCR. Check for signs of
physical damage.
NOTE: The PTCR case temperature may reach 210°F
(100°C) while the compressor is running. This is normal.
Do not change a PTCR just because it is hot.
2. Wait at least 10 minutes for the PTCR to cool to
room temperature.
3. Remove the PTCR from the ice machine.
4. Measure the resistance of the PTCR as shown
below. If the resistance falls outside of the
acceptable range, replace it.
Part No. 80-1100-3
! Warning
Manitowoc
Model
Part Number
Q200
Q280
Q320 8505003
Q420
Q450
Q600
Q800 8504993
Q1000
Q1300
Q1600 8504913
Q1800
Figure 6-17. Manitowoc PTCR's 8505003 & 8504993
Figure 6-18. Manitowoc PTCR 8504913
Electrical System
Room
Cera-Mite
Temperature
Part Number
Resistance
305C20 22-50 Ohms
305C19 18-40 Ohms
305C9 8-22 Ohms
SV1540
SV1541
6-43