Carrier Streamline Scroll 69NT20-531-300 - Manual (Page 74)

6-10 T-309
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 neces-
sary due to rapid heat dissipation
of the bi--metallic connections
Braze Rod
(’Sil-Phos” = 5.5% Silver, 6% Phosphorus)
Figure 6-12 Hermetic Thermostatic Expansion Valve Brazing Procedure
INLET
OUTLET
Figure 6-13 Economizer Expansion Valve
1. Pump down the unit per paragraph 6.4.
2. Remove cushion clamps located on the inlet and out-
let lines.
3. Unbraze the equalizer connection (if applicable), the
outlet connection and then the inlet connection.
4. Remove insulation (Presstite) from expansion valve
bulb.
5. Unstrap the bulb, located below the center of the suc-
tion line (4 o’clock position), and remove the valve.
b. Installing the Expansion Valve
1. Clean the suction line with sandpaper before instal-
ling bulb to ensure proper heat transfer. Apply ther-
mal grease to the indentation in the suction line.
2. Strap the thermal bulb to the suction line, making
sure bulb is placed firmly into the suction line. See
Figure 6-10 for bulb placement.
3. Insulate the thermal bulb.
4. The economizer expansion valves should be
wrapped in a soaked cloth for brazing. See
Figure 6-12. Braze inlet connection to inlet line
5. Braze outlet connection to outlet line.
6. Reinstall the cushion clamps on inlet and outlet
lines.
7. If applicable, braze the equalizer connection to the
equalizer line.
8. Check superheat (refer to step 6.14.1).
6.15 EVAPORATOR COIL AND HEATER
ASSEMBLY
The evaporator section, including the coil, should be
cleaned regularly. The preferred cleaning fluid is fresh
water or steam. Another recommended cleaner is Oakite
202 or similar, following manufacturer’s instructions.
The two drain pan hoses are routed behind the
condenser fan motor and compressor. The drain pan
line(s) must be open to ensure adequate drainage.
6.15.1 Evaporator Coil Replacement
a. Pump unit down. (Refer to paragraph 6.4.)
b. With power OFF and power plug removed, remove
the screws securing the panel covering the evaporator
section (upper panel).
c. Disconnect the defrost heater wiring.
d. Disconnect the defrost temperature sensor (see Fig-
ure Figure 2-2 from the coil. .
e. Remove middle coil support.
f. Remove the mounting hardware from the coil.
g. Unsolder the two coil connections, one at the distrib-
utor and the other at the coil header.
h. After defective coil is removed from unit, remove
defrost heaters and install on replacement coil.
i. Install coil assembly by reversing above steps.
j. Leak check connections per paragraph 6.5. Evacuate
the unit per paragraph 6.6 and add refrigerant charge
per paragraph 6.7.
6.15.2 Evaporator Heater Replacement
a.Before servicing unit, make sure the unit circuit break-
ers (CB-1 & CB-2) and the start-stop switch (ST) are
in the OFF position, and that the power plug and cable
are disconnected.
b. Remove the lower access panel (Figure 2-1) by
removing the T.I.R. locking device lockwire and
mounting screws.