Goodman AVPTC 14 Series Installation & Operating Instructions Manual page 8

Applying too much heat to any tube can melt the tube.
Torch heat required to braze tubes of various sizes must be
proportional to the size of the tube. Service personnel must
use the appropriate heat level for the size of the tube being
brazed.
7.3 Tubing Connections for TXV Models
TXV models come with factory installed TXV with the
bulb pre-installed on the vapor tube.
1. Remove refrigerant tubing panel or coil (lower) access
panel.
2. Remove access valve fitting cap and depress the valve
stem in access fitting to release pressure. No pressure
indicates possible leak.
3. Replace the refrigerant tubing panel.
4. Remove the spin closure on both the liquid and suction
tubes using a tubing cutter.
5. Insert liquid line set into liquid tube expansion and slide
grommet about 18" away from braze joint.
6. Insert suction line set into suction tube expansion and
slide insulation and grommet about 18" away from
braze joint.
7. Braze joints. Quench all brazed joints with water or a
wet rag upon completion of brazing.
NOTE: The sensing bulb must be permanently located. A
heat shield, heat trap, or wet rag must be used during braz-
ing to prevent damage to the TXV valve.
8. Replace access panels, suction line grommet, insula-
tion and all screws.
SUCTION LINE
WITH SPIN CLOSURE
SUCTION LINE GROMMET
7.4 Thermal Expansion Valve System Adjustment
The following information for the indoor unit should be
verified before attempting to charge system or adjust
TXV if necessary.
1. Total static pressure is .5" WC or less.
2. Airflow is correct for installed unit.
3. Airflow tables are in the installation manual and Spec
Sheet for Indoor Unit.
CAUTION
RUBBER
GROMMET
Figure 10
4. Complete airflow tables and charging information are in
Service Manual RS6200006.
5. The outdoor temperature must be 60°F or higher.
6. Set the room thermostat to COOL, fan switch to AUTO
7. Set the temperature control well below room temperature.
Superheat adjustments should not be made until indoor
ambient conditions have stabilized. This could take up to
24 hours depending on indoor temperature and humidity.
Before checking superheat run the unit in cooling for 10
minutes or until refrigerant pressures stabilize. Use the
following guidelines and methods to check unit operation
and ensure that the refrigerant charge is within limits. NOTE:
Charge two stage units 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 compres-
sor on the suction line. Ensure the thermometer makes
adequate contact and is insulated for best possible
readings. Use liquid line temperature to determine sub-
cooling and vapor temperature to determine superheat.
3. Check subcooling and superheat. The system should
have a subcooling of 8°F +/- 1°F and two-stage com-
pressor systems should have a Subcooling of 6°F +/-
1°F. and superheat of 8°F +/- 1°F. If subcooling and
superheat are low, adjust TXV to 8°F +/- 1°F superheat,
then check subcooling.
a. If subcooling is low and superheat is high, add
charge to raise subcooling to 8°F +/- 1°F. Two-
stage compressor systems should have a Subcool-
ing of 6°F +/- 1°F then check superheat.
b. If subcooling and superheat are high, adjust TXV
valve to 8°F +/- 1°F superheat, then check sub-
cooling.
Superheat Adjustments (Only if necessary)
1. Attach a pipe clamp thermometer near the suction line
service valve at the outdoor unit.
a. Ensure the thermometer makes adequate contact
for the best possible readings.
2. TXV-based systems should have a Superheat value of
8°F +/- 1°F.
3. Adjust Superheat by turning the TXV valve stem clock-
wise to increase and counterclockwise to decrease.
Adjustments should be made opening or closing the
valve by no more than ¼ turn at a time. Allow the sys-
tem to stabilize 15 to 20 minutes before making addi-
tional adjustments if necessary.
4. After adjustments are complete replace cap on adjust-
ment stem and tighten 1/6 turn.
5. Remove gauges and check the Schrader ports for
leaks and tighten valve cores if necessary. Install caps
finger tight.
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