5
7.3 Thermal Expansion Valve System Adjustment
Run the system at Cooling for 15 minutes until refrigerant
pressures stabilize. Use the following guidelines and
methods to check unit operation and ensure the refrigerant
charge is within limits. Charge the unit on low stage.
1. Purge gauge lines. Connect service gauge manifold to
base-valve service ports.
2. Temporarily install a thermometer on the liquid
line at the liquid line service valve and 4-6” from
the compressor on the suction line. Ensure the
thermometer makes adequate contact and is insulated
for best possible readings. Use liquid line temperature
to determine subcooling and vapor temperature to
determine superheat.
3. Check subcooling and superheat. System with TXV
should have a subcooling of 7 to 9°F and superheat of 7
to 9°F.
a. If subcooling and superheat are low, adjust TXV
to 7 to 9°F superheat, then check subcooling.
NOTE: To adjust superheat, turn the valve stem
clockwise to increase and counterclockwise to
decrease.
b. If subcooling is low and superheat is high, add
charge to raise subcooling to 7 to 9°F then
check superheat.
c. If subcooling and superheat are high, adjust
TXV valve to 7 to 9°F superheat, then check
subcooling.
WARNING
THIS PRODUCT IS FACTORY-SHIPPED WITH R410A AND DRY
NITROGEN MIXTURE GAS UNDER PRESSURE. USE APPRO
-
PRIATE SERVICE TOOLS AND FOLLOW THESE INSTRUC-
TIONS TO PREVENT INJURY.
8 Maintenance
Periodic Checkup and Service
This unit is designed to provide many years of dependable,
trouble-free comfort when properly maintained. Proper
maintenance will consist of annual checkups and cleaning
of the internal electrical and heat transfer components by
a qualified service technician. Failure to provide periodic
checkup and cleaning can result in excessive operating
cost and/or equipment malfunction.
