Therma-Stor Products Group 300 owner manual Defrost Thermostat and Timer, Condensate Pump

and water. These contaminants must be carefully removed otherwise even small residues will attack replacement compressor motors and cause failures.

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 non-burn out compressor.

2.Remove and properly dispose of the system charge. DO NOT vent the refrigerant or allow it to contact your eyes or skin.

3.Remove the burned out compressor. Use rubber gloves if there is any possibility of coming in contact with 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 have 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 capacitor and an oversized liquid line filter.

In a running burn out, install an oversized suction line filter/drier between the accumulator and compressor. Thoroughly flush the accumulator with refrigerant to remove all trapped sludge and to prevent 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.

8.Operate the system for a short period of time, monitoring 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 filter/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.

4.6C Replacing a Compressor- Non-Burn 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.

4.7 Defrost Thermostat and Timer

The defrost thermostat is attached to the refrigerant suction tube between the accumulator and compressor. If the low side refrigerant temperature drops due to excessive frost formation on the evaporator coil, the thermostat opens. The compressor is then cycled off and on by the defrost timer. The blower will continue to run, causing air to flow through the evaporator coil and melt the ice when the compressor is off. When the air temperature and/or humidity increase, the evaporator temperature will rise and the thermostat will close to end the defrost cycle.

To improve performance in low temperatures, see Sec. 2.9 for defrost timer adjustment.

4.8 Condensate Pump

Condensate is automatically pumped when the water level in the pump’s reservoir rises to close the float switch or if the pump purge switch is held in.

If the pump is unable to empty its reservoir due to a pump failure or blocked condensate hose, a pump safety float switch is triggered before the reservoir overflows. The switch turns on the pump fail light and turns off the compressor via its relay.

To replace the condensate pump:

1.Unplug the unit and remove the front cover.

2.Disconnect the 2 hoses from the pump.

3.Cut the pump lead wires near the old pump.

4.Remove the 4 screws from the unit bottom that hold the pump to the base.

5.Attach the new pump with 4 screws.

6.Connect the new pump wiring. It may be easier to splice the new and old gray leads together with a wire nut, and splice the new and old yellow leads together, rather than route the new ones to the pump purge switch and pump fail light.

7.Connect the hoses to the new pump. Carefully route the hoses so they do not contact the copper refrigerant lines or the compressor shell.

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