Carrier 69NT40-541-505, Operation And Service Manual, Page: 109 / 143

7–17 T-368
7.16.2 TXV Replacement
NOTES
1. The TXV is a hermetic valve, it does not have
adjustable superheat (See Figure 7.21 ).
2. All connections on the hermetic TXV are bi-
metallic, copper on the inside and stainless on
the outside.
3. All joints on the hermetic TXV (inlet, outlet and
equalizer lines) are brazed.
4. Bi-metallic connections heat up very quickly.
Figure 7.21 Thermostatic Expansion Valve
1. Hermetic Thermostatic Expansion Valve
2. Non-adjustable Superheat Stem
3. Equalizer Connection
4. Inlet Connection
5. Outlet Connection
6. Hermetic Expansion Valve Bulb
- - - - -
a. Removing the TXV:
1. Pump down the unit per Section 7.4 .
2. If TXV replacement is to be performed from the
front of the unit, open the upper right (EFM#1)
access panel (see
Figure 3.1 ) to remove evapo-
rator fan motor.
3. Remove cushion clamp that secures the valve
body to the bracket.
4. Unbraze the equalizer connection (1/4”), the out-
let connection (5/8”), and then the inlet connec-
tion (3/8”). See
Figure 7.23 . Be careful to protect
the insulation on the heaters and their wires.
5. Open the insulation flap. Flap is secured with
Velcro (Item 3, Figure 7.22 ).
6. Loosen the thumb screw and slide the bulb, out
by pulling it towards the front of the unit.
Figure 7.22 Hermetic Thermostatic Expansion
Valve Bulb Location
1. Hermetic Expansion Valve Bulb
2. Insulation
3. Insulation Flap
4. Velcro strip
5. Bulb Clamp
6. Thumb Screw
- - - - -
b. Installing the TXV
1. Braze inlet connection to inlet line (see Figure 7.23 ).
2. Braze outlet connection to outlet line.
3. Braze the equalizer connection to the equalizer line.
4. Reinstall the cushion clamp.
5. Thread the thermal bulb through the opening
above the evaporator coil (see Figure 3.2 ), and
slide it under the strap and secure the thumb
screw. Close the insulation flap. Reinstall bulb
access panel.
6. Check superheat (refer to step 7.16.1).
Figure 7.23 Hermetic Thermostatic Expansion Valve Brazing Procedure
1
2
3
4
5
6
1
2
3
4
5
6
Copper Tube
(Apply heat for 10-15 seconds)
Bi-metallic Tube Connection
(Apply heat for 2-5 seconds) Use of a wet cloth is not necessary due to rapid
heat dissipation of the bi-metallic connections
Braze Rod (’Sil-Phos” = 5.5% Silver, 6% Phosphorus)
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