Manitowoc QD0202A, Service Manual

Page: 132 / 175

Refrigeration System Section 7
7-20
Part No. 80-1100-3
SINGLE EXPANSION VALVE ICE MACHINES -
COMPARING EVAPORATOR INLET AND
OUTLET TEMPERATURES
NOTE: This procedure will not work on the dual
expansion valve Q1300 Q1600 and Q1800 ice
machines.
The temperatures of the suction lines entering and
leaving the evaporator alone cannot diagnose an ice
machine. However, comparing these temperatures
during the freeze cycle, along with using Manitowoc’s
Refrigeration System Operational Analysis Table, can
help diagnose an ice machine malfunction.
The actual temperatures entering and leaving the
evaporator vary by model, and change throughout the
freeze cycle. This makes documenting the “normal” inlet
and outlet temperature readings difficult. The key to the
diagnosis lies in the difference between the two
temperatures five minutes into the freeze cycle. These
temperatures must be within 7° of each other.
Use this procedure to document freeze cycle inlet and
outlet temperatures.
1. Use a quality temperature meter, capable of taking
temperature readings on curved copper lines.
2. Attach the temperature meter sensing device to the
copper lines entering and leaving the evaporator.
3. Wait five minutes into the freeze cycle.
4. Record the temperatures below and determine the
difference between them.
5. Use this with other information gathered on the
Refrigeration System Operational Analysis Table to
determine the ice machine malfunction.
Important
Do not simply insert the sensing device under the
insulation. It must be attached to and reading the
actual temperature of the copper line.
______________
Inlet Temperature
______________
Outlet Temperature
_______________
Difference
Must be within 7° at 5
minutes into freeze cycle