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TABLE 1
Compressor Operation
Unit Readings
Y1 −
1st-Stage
Expected Results
Y2 −
2nd-Stage
Compressor
Voltage
Same
Amperage
Higher
Condenser Fan motor
Amperage
Same or Higher
Temperature
Ambient
Same
Outdoor Coil Discharge Air
Higher in Cooling
Lower in Heating
Compressor Discharge Line
Higher
Indoor Return Air
Same
Indoor Coil Discharge Air
Lower in Cooling
Higher in Heating
Pressures
Suction (Vapor)
Lower
Liquid
Higher
STEP 2 Confirm DC voltage output on compressor
solenoid plug
A
− Compressor solenoid plug
WITH
built in full wave−
rectifier (LSOM I) that converts 24 volt AC into 24 volt
DC power. See Table 1 for units equipped with the
LSOM I.
1. Shut power off to outdoor unit.
2. Supply 24 volts AC control voltage to the wire ends
of the full wave rectifier plug. Listen for a click" as the
solenoid is energized. See figure 6.
compressor
solenoid fusite
terminals
compressor
fusite
terminals
meter
rectifier plug leads
apply 24vac
FIGURE 6
3. Unplug the full wave rectifier plug from the fusite
connection on the compressor.
4. Turn the low voltage power back onto the unit. Sup-
ply 24VAC to the wires of the full wave rectifier plug. Set
volt meter to DC volts and measure the DC voltage at
the female connector end of the full wave rectifier plug.
The DC voltage reading should be 1.5 to 3 volts lower
than the input voltage to the plug wire leads. (EX: Input
voltage is 24VAC output voltage is 22VDC).
See figure 7.
meter
rectifier plug leads
compressor
fusite
terminals
solenoid
fusite
terminals
compressor
apply 24vac
FIGURE 7
If the above checks verify that the solenoid plug is pro-
viding power to cycle into high capacity operation, con-
tinue to step 3 to determine if problem is with solenoid
coil in compressor
