SERVICING
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1. Remove outer case, control panel cover, etc., from unit being tested.
With power ON:
WARNING
Line Voltage now present.
2.Using a voltmeter, measure the voltage across terminals L1 and L2 of the contactor for the condensing unit or at the field connections for the air handler or heaters.
3.No reading - indicates open wiring, open fuse(s) no power or etc., from unit to fused disconnect service. Repair as needed.
4.With ample voltage at line voltage connectors, energize the unit.
5.Measure the voltage with the unit starting and operating, and determine the unit Locked Rotor Voltage. NOTE: If checking heaters, be sure all heating elements are energized.
Locked Rotor Voltage is the actual voltage available at the compressor during starting, locked rotor, or a stalled condition. Measured voltage should be above minimum listed in chart below.
To measure Locked Rotor Voltage attach a voltmeter to the run "R" and common "C" terminals of the compressor, or to the T1 and T2 terminals of the contactor. Start the unit and allow the compressor to run for several seconds, then shut down the unit. Immediately attempt to restart the unit while measuring the Locked Rotor Voltage.
6.Lock rotor voltage should read within the voltage tabula- tion as shown. If the voltage falls below the minimum voltage, check the line wire size. Long runs of undersized wire can cause low voltage. If wire size is adequate, notify the local power company in regard to either low or high voltage.
REMOTE CONDENSING UNITS
BLOWER COILS
VOLTAGE | MIN. | MAX. |
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208/230 | 198 | 253 |
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115 | 104 | 127 |
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NOTE: When operating electric heaters on voltages other than 240 volts, refer to the System Operation section on electric heaters to calculate temperature rise and air flow. Low voltage may cause insufficient heating.
1.Check wiring visually for signs of overheating, damaged insulation and loose connections.
2.Use an ohmmeter to check continuity of any suspected open wires.
3.If any wires must be replaced, replace with comparable gauge and insulation thickness.
S-3 CHECKING THERMOSTAT, WIRING, AND ANTICIPATOR
THERMOSTAT WIRE SIZING CHART
LENGTH OF RUN | MIN. COPPER WIRE | |
GAUGE (AWG) | ||
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25 feet | 18 | |
50 feet | 16 | |
75 feet | 14 | |
100 feet | 14 | |
125 feet | 12 | |
150 feet | 12 |
S-3A THERMOSTAT AND WIRING
WARNING
Line Voltage now present.
With power ON, thermostat calling for cooling
1.Use a voltmeter to check for 24 volts at thermostat wires C and Y in the condensing unit control panel.
2.No voltage indicates trouble in the thermostat, wiring or external transformer source.
3.Check the continuity of the thermostat and wiring. Repair or replace as necessary.
Indoor Blower Motor
With power ON:
WARNING
Line Voltage now present.
1.Set fan selector switch at thermostat to "ON" position.
2.With voltmeter, check for 24 volts at wires C and G.
3.No voltage indicates the trouble is in the thermostat or wiring.
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