Therma-Stor Products Group Ultra-Aire 100V - Manual (Page 11)

No dehumidification, compressor does not run but fan runs
with fan switch and ventilation timer OFF and humidity control
turned to ON.
1. Defective compressor run capacitor (Sec. 5.6).
2. Loose connection in compressor circuit (See Fig. 4).
3. Defective compressor overload (Sec. 5.6A).
4. Defective compressor (Sec. 5.6).
5. Defrost thermostat open (Sec. 5.8).
Fan runs with fan switch and ventilation timer OFF, but
compressor cycles on & off.
1. Low ambient temperature and/or humidity causing unit to
cycle through defrost mode.
2. Defective compressor overload (Sec. 5.6A).
3. Defective compressor (Sec. 5.6).
4. Defrost thermostat defective (Sec. 5.8).
5. Dirty air filter(s) or air flow restricted.
Fan does not run with fan switch in either position. Fan does
not run with ventilation timer activated. Compressor runs
briefly but cycles on & off with humidity control turned to ON.
1. Loose connection in fan circuit (See Fig. 4).
2. Obstruction prevents fan impeller rotation.
3. Defective fan.
4. Defective fan relay.
Fan runs with fan switch ON. Fan does not run with ventilation
timer activated.
1. Defective ventilation timer.
2. Time not correct on ventilation timer.
3. Ventilation timer set to manual & switched OFF.
Evaporator coil frosted continuously, low dehumidifying
capacity.
1. Defrost thermostat loose or defective (Sec. 5.8).
2. Low refrigerant charge
3. Dirty air filter(s) or air flow restricted.
4. Excessively restrictive ducting connected to unit.
Unit not providing ventilation. Ventilation timer notoperating
correctly.
1. If timer is not functioning correctly, reset timer and
reprogram (Sec. 3.5)
2. Check control wire connections (check connections at
damper also)
3. Defective fresh air damper (Sec. 5.9)
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.
FOR HVAC INSTALLER AND HOMEOWNER
11 Ultra-Aire 100V Installer’s & Owner’s Manual