Refrigerant Charging, Blower Replacement

5.4 Refrigerant Charging

If the refrigerant charge is lost due to service or a leak, a new charge must be accurately weighed in. If any of the old charge is left in the system, it must be removed before weighing in the new charge. Refer to the unit nameplate for the correct charge weight and refrigerant type.

5.5 Blower Replacement

The centrifugal blower has a PSC motor and internal thermal overload protection. If defective, the complete assembly must be replaced.

1.Unplug the power cord.

2.If an outlet duct is connected to the unit, remove it.

3.Remove the cabinet side.

4.Remove the 4 screws holding the electrical box located next to the blower.

5.Disconnect the blower leads. Black from the blower switch, and white the run capacitor.

6.Unbolt the blower capacitor from the blower motor (required for removal clearance). Pull the oil tubes out of the motor.

7.Remove the nuts & bolts holding the blower outlet flange to the cabinet end and remove the blower.

8.Reassembling with the new blower is the above procedure reversed.

5.6 Compressor/Capacitor Replacement

This compressor is equipped with a two terminal external overload, run capacitor, but no start capacitor or relay. See Fig. 2.

CAUTION-ELECTRICAL SHOCK HAZARD: Electrical power must be present to perform some tests; these tests should be performed by a qualified service person.

5.6A Checking Compressor Motor Circuits

Perform the following tests if the blower runs but the compressor does not with the blower switch OFF and the humidity control ON.

1.Unplug the unit, remove the cabinet side (with two screws in center) and the electrical connection cover on the compressor top.

2.Plug in the unit and turn the humidity control to ON. Check for 110 volts from compressor terminal R to overload terminal 3 using an AC voltmeter. If voltage is present, go to step 3. If no voltage, the high-pressure control or relay are open or there is a loose connection in the compressor circuit. Test each component for continuity; see the appropriate section if a defect is suspected.

3.Unplug the unit, then disconnect the red and yellow wires from compressor terminals R & S. Using an ohmmeter, check continuity between the points listed below.

4.Compressor terminals C and S: No continuity indi- cates an open start winding. The compressor must be replaced. Normal start winding resistance 3 to 7 ohms.

5.Compressor terminals C and R: No continuity indi- cates an open run winding. The compressor must be replaced. Normal run winding resistance is .5 to 2 ohms.

6.Compressor terminal C and overload terminal 1: No continuity indicates a defective overload lead.

7.Overload terminals 1 and 3: If there is no continuity, the overload may be tripped. Wait 10 minutes and try again. If there is still no continuity, it is defective and must be replaced.

8.Compressor terminal C and compressor case: Continuity indicates a grounded motor. The com- pressor must be replaced.

9.Disconnect the yellow wires from the capacitor. Set the ohmmeter to the Rx1 scale. The capacitor is shorted and must be replaced if continuity exists across its terminals. If there is no needle movement with the meter set on the Rx100000 scale, the capacitor is open and must be replaced.

10.Reconnect the wires to the compressor and capaci- tor. Plug in and turn on the unit. If the compressor fails to start, replace the run capacitor.

11.If the unit still doesn't start, adding a hard-start kit (relay & capacitor) will provide greater starting torque. If this doesn't work, the compressor has an internal mechanical defect and must be replaced.

5.6B Replacing a Burned Out Compressor

The refrigerant and oil mixture in a compressor is chemically very stable under normal operating conditions. However, when an electrical short occurs in the compressor motor, the resulting high temperature arc causes a portion of the refrigerant oil mixture to break down into carbonaceous sludge, a very corrosive acid, and water. These contaminants must be carefully removed otherwise even small residues will attack replacement compressor motors and cause failures.