Manitowoc QD0202A, Service Manual

Page: 121 / 175

Section 7 Refrigeration System
Part No. 80-1100-3
7-9
BEFORE BEGINNING SERVICE
Ice machines may experience operational problems only
during certain times of the day or night. A machine may
function properly while it is being serviced, but
malfunctions later. Information provided by the user can
help the technician start in the right direction, and may
be a determining factor in the final diagnosis.
Ask these questions before beginning service:
• When does the ice machine malfunction? (night, day,
all the time, only during the freeze cycle, etc.)
• When do you notice low ice production? (one day a
week, every day, on weekends, etc.)
• Can you describe exactly what the ice machine
seems to be doing?
• Has anyone been working on the ice machine?
• Is anything (such as boxes) usually stored near or on
the ice machine which could obstruct airflow around
the machine?
• During “store shutdown,” is the circuit breaker, water
supply or air temperature altered?
• Is there any reason why incoming water pressure
might rise or drop substantially?
ICE PRODUCTION CHECK
The amount of ice a machine produces directly relates to
the operating water and air temperatures. This means
an ice machine in a 70°F (21.1°C) room with 50°F
(10.0°C) water produces more ice than the same model
ice machine in a 90°F (32.2°C) room with 70°F (21.1°C)
water.
1. Determine the ice machine operating conditions:
Air temp. entering condenser: _______ °
Air temp. around ice machine: _______ °
Water temp. entering sump trough: _______ °
2. Refer to the appropriate 24 Hour Ice Production
Chart. (These charts begin on Page 7-33 .) Use the
operating conditions determined in Step 1 to find
published 24 hour ice production: ______
3. Perform an actual ice production check. Use the
formula below.
4. Compare the results of step 3 with step 2. Ice
production is normal when these numbers match
closely. If they match closely, determine if:
• another ice machine is required.
• more storage capacity is required.
• relocating the existing equipment to lower the
load conditions is required.
Contact the local Manitowoc distributor for
information on available options and accessories.
1.
__________
Freeze Time
+ __________
Harvest Time
= __________
Total Cycle Time
2.
1440
Minutes in 24
Hours
÷ __________
Total Cycle Time
= __________
Cycles Per Day
3.
__________
Weight of One
Harvest
x __________
Cycles Per Day
= __________
Actual 24 Hour Ice
Production
Important
Times are in minutes.
Example: 1 min., 15 sec. converts to 1.25 min.
(15 seconds ÷ 60 seconds = .25 minutes)
Weights are in pounds.
Example: 2 lb., 6 oz. converts to 2.375 lb.
(6 oz. ÷ 16 oz. = .375 lb.)
Weighing the ice is the only 100% accurate
check.
However, if the ice pattern is normal and the
1/8" thickness is maintained, the ice slab weights
listed with the 24 Hour Ice Production Charts may
be used.