The following procedure is effective only if the system is monitored after replacing the compressor to insure that the clean up was complete.
1.This procedure assumes that the previously listed compressor motor circuit tests revealed a shorted or open winding. If so, cautiously smell the refrigerant from the compressor service port for the acid odor of a burn out.
WARNING: The gas could be toxic and highly acidic. If no acid odor is present, skip down to the section on changing a
2.Remove and properly dispose of the system charge. DO NOT vent the refrigerant indoors or allow it to contact your eyes or skin.
3.Remove the burned out compressor. Use rubber gloves if there is any possibility of contacting the oil or sludge.
4.To facilitate subsequent steps, determine the type of burn out that occurred. If the discharge line shows no evidence of sludge and the suction line is also clean or perhaps has some light carbon deposits, the burn out occurred while the compressor was not rotating. Contaminants are therefore largely confined to the compressor housing. A single installation of liquid and suction line filter/driers will probably clean up the system.
If sludge is evident in the discharge line, it will likely be found in the suction line; this indicates the compressor burned out will running. Sludge and acid has been pumped throughout the system. Several changes of the liquid and suction filter/driers will probably be necessary to cleanse the system.
5.Correct the system fault that caused the burn out. Consult the factory for advice.
6.Install the replacement compressor with a new ca- pacitor and an oversized liquid line filter.
In a running burn out, install an oversized suction line filter/drier between the accumulator and com- pressor. Thoroughly flush the accumulator with re- frigerant to remove all trapped sludge and to pre- vent the oil hole from becoming plugged. A standing burn out does not require a suction line filter/drier.
7.Evacuate the system with a good vacuum pump and accurate vacuum gauge. Leave the pump on the system for at least an hour.
An alternate method of removing moisture and non- condensibles from the system requires evacuation to 29" Hg vacuum. Then break the vacuum with 35 to 50 PSIG refrigerant vapor charge. Leave the vapor charge in the system for at least 5 minutes before removing it. Repeat the vapor charge/wait/remove sequence twice more and then charge the system with the quantity and refrigerant listed on the nameplate.
8.Operate the system for a short period of time, moni- toring the suction pressure to determine that the suction filter is not becoming plugged. Replace the suction filter/drier if pressure drop occurs. If a severe running burn out has occurred, several fil- ter/driers may have to be replaced to remove all of the acid and moisture.
NOTE: NEVER use the compressor to evacuate the system or any part of it.
5.6C Replacing a Compressor- Nonburn Out
Remove the refrigerant from the system. Replace the compressor and liquid line filter/drier. Charge the system to 50 PSIG and check for leaks. Remove the charge and weigh in the refrigerant quantity listed on the nameplate. Operate the system to verify performance.
5.7 Humidity Control
The humidity control is an adjustable switch that closes when the relative humidity of the air in which it is located rises to the dial set point. It opens when the RH drops 4 to 6% below the set point.
5.8 Defrost Thermostat
The defrost thermostat is attached to the refrigerant suction tube between the accumulator and compressor. It will automatically shut the compressor off if the low side refrigerant temperature drops due to excessive frost formation on the evaporator coil. The blower will continue to run, causing air to flow through the evaporator coil and melt the ice. When the ice has melted, the evaporator temperature will rise and the thermostat will restart the compressor.
5.9 Condensate Pump
Condensate is automatically pumped to a remote location when the water level in the pump's reservoir rises to close the float switch.
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