Removal And Replacement - Scotsman UC2024 Series Service Manual

UC2024 and UC2724 Service Manual

Removal and Replacement

Compressor: Test First
Failure to start.
Check voltage to compressor at the contactor.
Compare the idle voltage (compressor off) to the
active voltage (compressor starting). The supply
voltage must not be less than the lowest rated voltage
for the ice machine. If the voltage is correct, proceed
to the next step.
Check starting components. The UC2724 model
uses a PTCR to cut power to the start winding after
the compressor has started. Check the PTCR for
resistance. The resistance check must be when the
PTCR is at room temperature – any temperature
between 50 and 100. At that temperature resistance
should be very low between 25 and 50 ohms. Also
check resistance to ground, it should be infinite. If the
PTCR is good, check the compressor windings.
Measure resistance from Common to ground. It
should be infinite. Measure resistance from Common
to Run – compare to the chart. Measure resistance
from Common to Start – compare to the chart.
Note: Chart referenced is from compressor mfg.
Compressor check for high amp draw. Measure
amp draw of starting circuit. If it does not drop off
immediately after start up, the PTCR should be
replaced. It is not practical to check a PTCR for
resistance at high temperatures as the resistance
drops very fast as the PTCR's temperature falls. If
the compressor is drawing excessive amps but is
operating, the run capacitor may be open.
Disconnect electrical power, discharge the capacitor
and measure its resistance. If open, replace it. If
shorted to ground, replace it.
Any time the compressor is replaced, the PTCR and
run capacitor should also be replaced, or if the model
was equipped with a potential relay, start capacitor
and run capacitor, those should be replaced with the
compressor. Most Scotsman service compressors
include those parts.
Remove and Replace
1. Disconnect Electrical Power
2. Remove front and lower back panels.
3. Remove top and right side panels.
4. Recover refrigerant
5. Remove electrical connections from compressor
6. Unsweat process, suction and discharge tubes
from compressor.
7. Remove fasteners holding compressor to base
and lift compressor from unit.
8. Confirm new compressor is the correct one for the
unit.
9. Remove old dryer from unit.
10. Place in unit.
11. Braze the suction, discharge and process tubes
onto the new compressor using the methods and
procedures of the refrigeration trade for that work.
12. Braze a new dryer into the liquid line where the
original one was.
13. Evacuate the system to 300 microns.
14. Weigh in the nameplate charge.
15. Attach the electrical connections to the
compressor.
16. Restart and test for proper operation.
November 2019
Page 31
Electrical Shock Hazard
Disconnect electrical
power before beginning