18-AD28D1-2
11
Installer’s Guide
O. REPLACING A TXC***S3 COIL WITH A
4NXC****C3 COIL (4NXCB032, 4NXCB036, and
4NXCB063 Coil Only)
1. Determine which refrigerant is being used by the
system. This coil is shipped ready for R-410A. The
TXV is correct for R-410A systems only.
2. Recover refrigerant in the system.
3. Disconnect refrigerant lines.
4. Disconnect drain lines.
5. Slide the old coil out.
6. Discard the coupling panel and front access panel from
the existing AS3 cabinet.
7. Slide the new coil in the place of the old coil.
8. Install the manifold panel from the new 4NXC coil
cabinet to the existing coil cabinet.
IMPORTANT:
When unbrazing and brazing lines, make sure to wrap a
wet rag around the liquid or suction line before the TXV
body to protect the TXV from over heating during brazing.
NOTE:
TXV bulb MUST be protected (wrapped with wet rag) or
removed, while brazing the tubing. Overheating of the
sensing bulb will affect the functional characteristics and
performance of the comfort coil.
9. Wrap a wet rag around the suction line before the TXV
sensing bulb to protect the bulb from over heating
during brazing.
10. Wrap a wet rag around the liquid line before the TXV
body to protect the TXV from over heating during
brazing.
11. Connect the field refrigerant lines. Brazing instructions
are on page 7.
12. Leak test all refrigerant piping with dry nitrogen.
13. Remove the wet rags.
14. Install the front panel from the new 4NXC coil cabinet
to the existing coil cabinet.
15. Replace the condensate drain piping per the coil
installation instructions on page 8.
16. Pull a vacuum on the refrigerant system.
17. Charge the system per the charging instructions with
the outdoor unit
P. TXV CHANGE OUT
1. Unbraze the liquid line field connection.
2. Remove the front panel and manifold panel.
3. Slide the coil out of the cabinet.
3. Snip the wire tie on the TXV and discard. Disconnect
the TXV sensing bulb and equalizer line.
4. Remove old TXV. Make sure to use a backup wrench
when loosening TXV. See Figure 21.
5. Attach the new TXV to the coil distributor assembly.
Make sure to use backup wrench as shown in Figure
21. Align the liquid line tube with the hole in the
manifold panel. Use a field supplied wire tie to attach
the TXV to the TXV mount bracket.
6. Connect the Equalizer line to the brass fitting on the
suction manifold.
7. Attach the TXV sensing bulb to the suction manifold.
The bulb should be between the 8 - 4 o’clock position on
the line.
8. Insulate the TXV sensing bulb.
9. Replace the manifold and front panels.
IMPORTANT:
When unbrazing and brazing lines, make sure to wrap a
wet rag around the liquid or suction line before the TXV
body to protect the TXV from over heating during brazing.
NOTE:
TXV bulb MUST be protected (wrapped with wet rag) or
removed, while brazing the tubing. Overheating of the
sensing bulb will affect the functional characteristics and
performance of the comfort coil.
10. Wrap a wet rag around the liquid line before the TXV
body to protect the TXV from over heating during
brazing.
11. Braze the field Liquid line to the coil.
12. Pressure test the refrigerant system using dry
nitrogen. Test all connections for leaks to ensure
integrity of the refrigerant piping system.
NOTE:
Torque specification for TXV equals 1/6 turn past finger
tight. Make sure to use a backup wrench when tightening
or loosening TXV. See Figure 21.
Figure 21
