Section 7 Refrigeration System
7-29
LOW ON CHARGE VERIFICATION
The remote ice machine requires more refrigerant
charge at lower ambient temperatures than at higher
temperatures. A low on charge ice machine may
function properly during the day, and then
malfunction at night. Check this possibility.
If you cannot verify that the ice machine is low on
charge:
1. Add refrigerant in 2 lb. increments, but do not
exceed 6 lbs.
2. If the ice machine was low on charge, the
headmaster function and discharge pressure will
return to normal after the charge is added. Do
not let the ice machine continue to run. To
assure operation in all ambient conditions, the
refrigerant leak must be found and repaired, the
liquid line drier must be changed, and the ice
machine must be evacuated and properly
recharged.
3. If the ice machine does not start to operate
properly after adding charge, replace the
headmaster.
FAN CYCLE CONTROL VS. HEADMASTER
A fan cycle control cannot be used in place of a
headmaster. The fan cycle control is not capable of
bypassing the condenser coil and keeping the liquid
line temperature and pressure up.
This is very apparent when it rains or the outside
temperature drops. When it rains or the outside
temperature drops, the fan begins to cycle on and
off. At first, everything appears normal. But, as it
continues raining or getting colder, the fan cycle
control can only turn the fan off. All the refrigerant
must continue to flow through the condenser coil,
being cooled by the rain or low outside temperature.
This causes excessive sub-cooling of the refrigerant.
As a result, the liquid line temperature and pressure
are not maintained for proper operation.
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