Ultra-Aire SD12 Installer’s & Owner’s Manual
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wiring.
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. Add 53 oz. of HFC-410A plus 2.2 oz. HFC-410A for every
10 feet of line set length to calculate the total refrigerant charge
required. Refer to Section 3.7 for charging procedure.
WARNING!
ELECTRIC SHOCK HAZARD. CAN CAUSE
INJURY OR DEATH. UNIT MUST BE GROUNDED IN ACCORDANCE
WITH NATIONAL AND LOCAL CODES. DISCONNECT ALL REMOTE
ELECTRIC POWER SUPPLIES BEFORE OPENING ACCESS PANEL.
UNIT MAY HAVE MULTIPLE POWER SUPPLIES.
7.5 Dehumidifier Impeller Fan Replacement
The motorized impeller fan is a unitary assembly consisting of the
motor and impeller fan. If defective, the complete assembly must
be replaced. See Figure 18B.
1. Unplug the dehumidifier power cord.
2. Remove the cabinet access panel.
3. Disconnect the wires from the dehumidifier fan run capacitor.
Safely discharge the run capacitor. Measure the capacitance
of the capacitor using a capacitance meter. Check the capaci-
tance measurement against the capacitor marked capacitance.
Replace the capacitor if the measured capacitance is not within
10% of the marked capacitance. If a capacitance meter is not
available, an analog ohmmeter can be used to test 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.
4. Remove the impeller fan support bracket.
5. Disconnect the impeller fan leads inside the electric box.
6. Remove the defective impeller fan from the bracket and replace
with it with a new impeller fan.
7. Reassemble the new impeller fan by reversing the above proce-
dure.
Note:
be sure that the impeller fan aligns with the inlet ring
inside of the dehumidifier.
7.6 Condensing Unit Fan/Blade Replacement
Perform the following tests if the dehumidifier impeller fan and
compressor run, but the condensing unit fan does not.
1. Disconnect the condensing unit power supply. See FIGURE 18C.
2. Remove the cabinet top panel.
3. Disconnect the wires from the condensing unit fan run capaci-
tor. Safely discharge the run capacitor. Measure the capacitance
of the capacitor using a capacitance meter. Check the capaci-
tance measurement against the capacitor marked capacitance.
Replace the capacitor of the measured capacitance is not within
10% of the marked capacitance. If a capacitance meter is not
available, an analog ohmmeter can be used to test 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
FOR HVAC INSTALLER ONLY
scale, the capacitor is open and must be replaced.
4. Mark the location of the fan blade on the motor shaft. Remove
the fan blade from the motor shaft and slide it to the front of the
condensing unit.
5. Disconnect the fan leads inside the electric box.
6. Remove the defective fan motor from the bracket.
7. Transfer the mark for the fan blade location to the new fan motor
shaft.
8. Attach the new fan motor to the bracket.
9. Slide the fan blade on to the new motor shaft until it is aligned with
the mark you transferred. Attach the fan blade to the motor shaft.
10. Reconnect the fan leads inside the electric box.
11. Install the cabinet top panel.
12. Reconnect the condensing unit power supply.
7.7 Compressor/Capacitor Replacement
This compressor is equipped with a two terminal external overload and
a run capacitor (See FIGURE 18C).
7.7A Checking Compressor Motor Circuits
Perform the following tests if the dehumidifier impeller fan and
condensing unit fan run but the compressor does not with a call for
dehumidification.
1. Disconnect power from the condensing unit; remove the cabinet top
and the electrical connection cover on the compressor top.
2. Reconnect power to the condensing 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. Disconnect power from the condensing unit, and then disconnect
the red and brown 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 indi-
cates 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, the overload 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 compressor run capacitor. Safely
discharge the run capacitor. Measure the capacitance of the capaci-
tor using a capacitance meter. Check the capacitance measurement
against the capacitor marked capacitance. Replace the capacitor of
the measured capacitance is not within 10% of the marked capaci-
tance. If a capacitance meter is not available, an analog ohmmeter
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