Lennox HPXA16 series, Unit Information

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Page 6
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
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 so-
lenoid 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 con-
nection on the compressor.
4. Turn the low voltage power back onto the unit. Supply
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
STEP 3 Confirm internal unloader solenoid has prop-
er resistance
1. Shut all power off to unit (main and low voltage)
2. Unplug the molded plug from the compressor solenoid
2−pin fusite.
3. Using a volt meter set on the 200 ohm scale
Replace the Compressor under these conditions:
Bad Solenoid
a. Measure the resistance at the 2−pin fusite.The resist-
ance should be 32 to 60 ohms depending on compressor
temperature. If no resistance replace compressor.
b. Measure the resistance from each fusite pin to ground.
There should
not be continuity to ground. If solenoid coil
is grounded, replace compressor.
Good Solenoid
a. Seals not shifting, replace compressor
b. Slider ring not shifting, replace compressor.