Midea MCCDH30A-TA3SL, Technical & Service Manual

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Air-cooled modular chiller unit
1
1 Maintenance
Maintenance for main components
：
● Close attention should be paid to the discharge and suction pressure during the running process. Find out
reasons and eliminate the failure if abnormality is found.
● Control and protect the equipment. See to it that no random adjustment be made on the set points on site.
● Regularly check whether the electric connection is loose, and whether there is bad contact at the contact
point caused by oxidation and debris etc., and take timely measures if necessary. Frequently check the work
voltage, current and phase balance.
● Check the reliability of the electric elements in time. Ineffective and unreliable elements should be
replaced in time.
Removing scale
After long-time operation, calcium oxide or other minerals will be settled in the heat transfer surface of the
water-side heat exchanger. These substances will affect the heat transfer performance when there is too
much scale in the heat transfer surface and sequentially cause that electricity consumption increases and
the discharge pressure is too high (or suction pressure too low). Organic acids such as formic acid, citric
acid and acetic acid may be used to clean the scale. But in no way should cleaning agent containing chlorine
acid or fluoride should be used as the water-side heat exchange is made from stainless steel and is easy to
be eroded to cause refrigerant leakage. Pay attention to the following aspects during the cleaning and
scale-removing process:
● Water-side heat exchanger should be done be professionals.
● Clean the pipe and heat exchanger with clean water after cleaning agent is used. Conduct water treatment
to prevent water system from being eroded or re-absorption of scale.
● In case of using cleaning agent, adjust the density of the agent, cleaning time and temperature according
to the scale settlement condition.
● After pickling is completed, neutralization treatment needs to be done on the waste liquid. Contact relevant
company for treating the treated waste liquid.
● Protection equipment (such as goggles, gloves, mask and shoes) must be used during the cleaning
process to avoid breathing in or contacting the agent as the cleaning agent and neutralization agent is
corrosive to eyes, skins and nasal mucosa.
Winter shutdown
For shutdown in winter, the surface of the unit outside and inside should be cleaned and dried. Cover the
unit to prevent dust. Open discharge water valve to discharge the stored water in the clean water system to
prevent freezing accident (it is preferable to inject antifreeze in the pipe).
Replacing parts
Parts to be replaced should be the ones provided by our company. Never replace any part with different part.
First startup after shutdown
The following preparations should be made for re-startup of unit after long-time shutdown:
1) Thoroughly check and clean the unit.
2) Clean water pipe system.
3) Check pump, control valve and other equipment of water pipe system.
4) Fix connections of all wires.
5) It is a must to electrify the machine before startup.
Refrigeration system
Determine whether refrigerant is needed by checking the value of suction and discharge pressure and check
whether there is a leakage. Air tight test must be made if there is a leakage or parts of refrigerating system is
to be replaced. Take different measures in the following two different conditions from refrigerant injection.
1) Total leakage of refrigerant. In case of such situation, leakage detection must be made on the pressurized
nitrogen used for the system. If repair welding is needed, welding cannot be made until all the gas in the