Labconco FreeZone Plus 4.5 Liter and FreeZone -105 C Cascade Freeze Dry Systems 73870 Series - Manual (Page 40)

Chapter 7: Troubleshooting
Product Service 816-333-8811 or 1-800-522-7658 36
Refrigeration Module Operation
Under a no-load condition, FreeZone Plus Cascade Freeze Dry Systems
should achieve a collector temperature of –84°C (models 73860xx and
73870xx) or -105°C (models 73820xx) or lower when the vacuum pump is
operating. If the collector temperature does not reach the design temperature
within 30 minutes, then the refrigeration module is not functioning properly.
Cascade Systems consist of two vapor-compression refrigeration systems in
series connected together via a heat exchanger. Each system has a
compressor, condenser, capillary tube metering device and an evaporator.
During the operation the evaporator of the “high stage” system refrigerates
the condenser of the “low stage” system. This takes place in the heat
exchanger. The low stage and high stage systems are balanced by design,
however, sometimes that balance can be disrupted during operation and the
unit will not function properly. If the unit is overloaded, or if the unit is
defrosted and restarted in a short time interval, system unbalance is possible.
If system unbalance occurs, turn the freeze dryer off and allow the unit to
stabilize at ambient temperature for 2 to 4 hours.
If any repairs are required on the refrigeration module, contact your local
laboratory supply dealer. If your laboratory supply dealer is unable to
provide assistance, please call Labconco. Repairs should only be undertaken
by a refrigeration technician or through an authorized Labconco service
agency.