1. Defective compressor run capacitor (Sec. 7.6).
2. Loose connection in compressor circuit.
3. Defective compressor overload (Sec. 7.6A).
4. Defective compressor (Sec. 7.6).
5. Defrost thermostat open.
Compressor cycles on and off. Dehumidification is being called
for. No fan call
1. Low ambient temperature and/or humidity causing unit to
cycle through defrost mode.
2. Defective compressor overload (Sec. 7.6A).
3. Defective compressor (Sec. 7.6).
4. Defrost thermostat defective (Sec. 7.8).
5. Dirty air filter(s) or air flow restricted.
Fan is not running. Dehumidification or fan is being called for
1. Loose connection in fan circuit.
2. Obstruction prevents fan impeller rotation.
3. Defective fan.
4. Defective fan relay.
Low dehumidification capacity (evaporator is frosted
continuously). Dehumidification is being called for
1. Defrost thermostat loose or defective (Sec. 7.8).
2. Low refrigerant charge
3. Dirty air filter(s) or air flow restricted.
4. Excessively restrictive ducting connected to unit.
No ventilation. Ventilation is being called for.
1. Loose connection in ventilation control circuit
2. Loose connection in damper power circuit.
3. Defective fresh air damper.
7.4 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 recovered before weighing in the new
charge. Refer to the unit nameplate for the correct charge weight
and refrigerant type.
7.5 Fan Replacement
The centrifugal fan 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 3 screws attaching the electrical box located in
front of the fan to the base.
5. Disconnect the fan leads. Black from the fan relay and white
from the run capacitor.
6. Remove the nuts & bolts holding the fan outlet flange to the
cabinet end and remove the fan.
7. Reassemble the new fan by reversing the above procedure.
7.6 Compressor/Capacitor Replacement
This compressor is equipped with a two terminal external overload
and a run capacitor, but no start capacitor or relay (See Figure 4).
CAUTION-ELECTRICAL SHOCK HAZARD:
Electrical power must be present to perform
some tests. These tests should be performed
by a qualified service person.
7.6A Checking Compressor Motor Circuits
Perform the following tests if the fan runs but the compressor does
not with the fan switch OFF and the humidity control ON.
1. Unplug the unit, remove the cabinet side 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, there may be 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 indicates an open start winding. The
compressor must be replaced. Normal start winding
resistance is 3 to 7 ohms.
5. Compressor terminals C and R:
No continuity indicates 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 compressor must be
replaced.
9. Disconnect the wires from the run 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.
FOR HVAC INSTALLER AND HOMEOWNER
8
Ultra-Aire 100V Installer’s & Owner’s Manual
