Flooded type water cooled screw chiller (PCB Control)
MCAC-CTSM-2012-11
74
water temperature rises up to 13
℃
, the safety resets and the chiller restarts. Besides, the chillers are
equipped with antifreeze switch which located on the outlet of chilled water. If leaving water temperature
continuously keeps lower than 3 °C for 3s during operation, the chiller will be shut down. When water
temperature rises up to 10 °C, the chiller resets, but it needs manually reset on the touch screen.
IMPORTANT:
If unit is installed in an area where ambient temperature may fall below 32 F (0° C), a
suitable corrosion-inhibited antifreeze solution or auxiliary electric heater must be used in the chilled
water circuit.
Relief Devices
Pressure relief valves
Relief valves are installed on evaporator, condenser and oil separator. These valves are designed to
relieve if an abnormal pressure condition arises. Relief valves on condenser relieve at 1.55MPa. These
valves should not be capped. If a valve relieves, it should be replaced. If not replaced, it may relieve at a
lower pressure compared to the set point, or leak due to trapped dirt from the system which may prevent
resealing.
Control Modules
• Main base board (mbb), screwcompressor Board (scb), expansion valve board (exv), Energy
management module (emm), Comfortlink™compressor protection Board (ccp), and the navigator
• Red led
• Green led
• Yellow led
Replacing Defective PCB Controller
For Midea screw chiller, it adopts special refrigeration PCB controller. The program and data is written
into the memory by Midea in the replacement module. When ordering any replacement module, specify
the model of unit and information of user (Name/Country/Installation time of unit). Return the faulted
module to Midea.
Caution
：
Electrical shock can cause personal injury. Disconnect all electrical power before servicing.
1
）
Check that all power to unit is off. Carefully disconnect all wires from the defective module by
unplugging its connectors. Remove the defective module by removing its mounting screws with a Phillips
screwdriver, and removing the module from the electric control box. Save the screws in an appropriate
place for later use.
2
）
Package the defective module in the carton of the new module for return to Midea.
3
）
Install the new module in the unit’s control box using a Phillips screwdriver and the screws saved
before.
4
）
Reinstall all module connectors and communication wire. Carefully check all wiring connections
before restoring power. Make sure the connectors are installed at the right place.
5
）
Restore control power. Verify all configuration information, settings, set points and schedules.