27
Troubleshooting Guide -
Tranquility
®
Digital (DXM2) Packaged Units
Rev.: 01/15/14
Determining Sub-Cooling:
1. Measure the temperature of the liquid line. Note that the location of the liquid line changes, depending upon the mode
(heating or cooling) for packaged units. For split units, measure liquid line temperature at the compressor section. Liquid
line does not change on a split system.
2. Determine the condenser pressure (High Side) by attaching refrigerant gauges to the schrader connection on the hot gas
discharge line of the compressor.
3. Convert the pressure obtained in step 2 above to the boiling point temperature by using the Press/Temp conversion table or
the gauge set.
4. Subtract the temperature of Step 3 from the temperature of Step 1. The difference will be the sub-cooling value for that unit
(total degrees below the boiling point). Refer to the sub-cooling Table 1 for values at specifi c entering water temperatures.
Example (HFC-410A):
The condenser pressure at the high pressure service port is 340 psig, which is equivalent to 105°F. The liquid line (between the air
coil and TXV in heating; between the coax and TXV in heating) measures 95°F
.
95°F subtracted from 105°F = 10°F sub-cooling
Consult the specifi c equipment information for refrigeration conditions. If a problem is suspected consult
troubleshooting charts in unit IOM.
Compressor
Expansion
Device
Coax
HWG
RV
Air
Coil
Suction
Discharge
Heating Cycle
Digital
Thermometer
Subcooling = High Pressure Saturation Temperature - Liquid Line Temperature
Heating Liquid Line (LT2)
Cooling Liquid Line (LT1)
Measuring Subcooling
Refrigeration Troubleshooting
A-H
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