Replacing The Compressor - Liebert DM User Manual

56 Chapter 6 System O&M

6.1.8 Replacing The Compressor


Warning
No direct contact between the refrigerant or lubricant and the skin when replacing the compressor, or serious burning or frostbite
may occur. Put on gloves with long sleeves when processing polluted parts.
The Liebert_DM 16kW system uses the highly reliable Copeland scroll compressor. If handled properly, the failure rate
is extremely low.
It is rare for the motor of the compressor to get burned due to short circuit. In the few cases when the motor does get
burned, the cause is usually mechanical or due to poor lubrication, in other words, due to over-temperature.
If the causes that lead to the compressor failure could be discovered and corrected in time, most failures are avoidable.
The maintenance personnel should check the operation situation periodically and take necessary measures to ensure
the system normal operation. This practice is both easy and cost saving, when you compare it with replacing the
compressor upon faults that result from negligence.
When diagnosing the compressor, check the operation situation of all the electric parts of the compressor.
1. Check all the fuses and circuit breakers.
2. Check the operation of HP and LP switches.
3. When the compressor is faulty, find out the nature of the cause: is it an electrical fault or a mechanical fault?
For mechanical faults
Upon a mechanical fault, there is no burned smell. You should try spinning the motor. If the fault is proved to be
mechanical, the compressor has to be replaced. If the motor is burned, you should remove the fault that leads to the
burning of the motor and clean the system. It must be pointed out that the compressor motor is usually burned
because the system is not cleaned properly.
For electric faults
You can tell an electric fault by the unpleasant smell. If serious burning occurred, the lubricant will appear black and
become acid. When electric fault occurs and the compressor motor is entirely burned, the system must be cleaned to
remove the acid material from the system and to avoid such faults in the future.

Note
The damage to the compressor components due to improper way of cleaning is classified in the warranty agreement as improper
usage of the product, thus is not covered by the warranty.
When the compressor is entirely burned, you need to replace the filter drier together with the compressor. In addition,
check the expansion valve. If the valve is faulty, replace it too. Before the replacement, you must clean the system. If
you are unsure about the cleaning method, please consult with Emerson service personnel.
Compressor replacing procedures
1. Cut off the power supply.
2. Connect the LP and HP tubes of the pressure gauge to the needle valves of the suction and exhaustion pipes
respectively to recycle the refrigerant.

Note
The refrigerant must be recycled or disposed in accordance with the local regulations. Discharging the refrigerant into the air is
harmful to the environment and illegal.
3. Disconnect all the electric connection to the compressor.
4. Disconnect the Rotalocks from the exhaust and suction openings on the compressor.
5. Remove the faulty compressor.
6. If the compressor has been entirely burned, you need to clean the pipes of the cooling system and replace the filter
drier.

Note
Do not remove the rubber covers from the suction opening and exhaust opening of the new compressor too early. The time that
the openings are exposed to the air should not exceed 15mins so as to prevent the compressor refrigeration oil from absorbing
water and bringing the water into the system.
DM Series 16kW Air Conditioner User Manual