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122
Thermostatic Expansion Valve (TXV) —
Each circuit
has a TXV. The TXV is nonadjustable and is factory set to main-
tain 10 to 13° F superheat leaving the evaporator coil. The TXV
controls flow of liquid refrigerant to the evaporator coils.
Gas Valve Adjustment
NATURAL GAS — The 2-stage gas valve opens and closes
in response to the thermostat or limit control.
When power is supplied to valve terminals 3 and 4, the pilot
valve opens to the preset position. When power is supplied to
terminals 1 and 2, the main valve opens to its preset position.
The regular factory setting is stamped on the valve body
(3.5 in. wg).
To adjust regulator:
1. Set thermostat at setting for no call for heat.
2. Turn main gas valve to OFF position.
3. Remove
1
/
8
-in. pipe plug from manifold. Install a water
manometer pressure-measuring device.
4. Set main gas valve to ON position.
5. Set thermostat at setting to call for heat (high fire).
6. Remove screw cap covering regulator adjustment screw
(See Fig. 40).
7. Turn adjustment screw clockwise to increase pressure or
counterclockwise to decrease pressure.
8. Once desired pressure is established, set unit to no call for
heat (3.3-in. wg high fire).
9. Turn main gas valve to OFF position.
10. Remove pressure-measuring device and replace
1
/
8
-in.
pipe plug and screw cap.
11. Turn main gas valve to ON position and check heating
operation.
Main Burners —
For all applications, main burners are
factory set and should require no adjustment.
MAIN BURNER REMOVAL (Fig. 41)
1. Shut off (field-supplied) manual main gas valve.
2. Shut off power supply to unit.
3. Remove heating access panel.
4. Disconnect gas piping from gas valve inlet.
5. Remove wires from gas valve.
6. Remove wires from rollout switch.
7. Remove sensor wire and ignitor cable from IGC board.
8. Remove 2 screws securing manifold bracket to basepan.
9. Remove 4 screws that hold the burner support plate
flange to the vestibule plate.
10. Lift burner assembly out of unit.
11. Reverse procedure to re-install burners.
Filter Drier —
Replace whenever refrigerant system is ex-
posed to atmosphere.
Replacement Parts —
A complete list of replacement
parts may be obtained from any Carrier distributor upon request.
Fig. 41 — Main Burner Removal
OFF
ON
W-1
W-2
D-1 D-2
C1
C2
PILOT
ADJ.
INLET PRESSURE TAP
(PLUGGED)
1/8 - 27 N.P.T. THDS.
2 LEADS, #18 WIRE 1/32 INSULATION,
600V. MAX., 105
°
C
REGULATOR
ADJUSTMENT SCREW
(REMOVE COVER)
OUTLET PRESSURE
TAP (PLUGGED)
1/8-27 N.P.T. THDS.
PILOT CONNECTION
FOR 1/4” O.D. TUBING
(PLUGGED)
RECEPTACLE AND
TAB COMBINATION
TERMINAL
RECEPTACLE TERMINAL
Fig. 40 — Gas Valve (Part Number EF33CB271)
Fig. 39 — Condenser-Fan Adjustment
A48-3730
A48-5717
A48-3733
Fig. 38 — Belt Tension Adjustment
A48-3729
Summary of Contents for WEATHERMAKER 48AJ020
Page 95: ...95 Fig 13 Typical Main Control Box Wiring Schematic A48 7787 ...
Page 96: ...96 TO NEXT PAGE Fig 14 Auxiliary Control Box Wiring Schematic A48 7294 ...
Page 98: ...98 Fig 15 Typical 2 Stage Gas Heat Wiring Schematic Size 051 and 060 Units Shown A48 6866 ...
Page 102: ...102 TO NEXT PAGE Fig 18 Typical Power Schematic Size 051 and 060 Units Shown A48 7298 ...
Page 104: ...104 Fig 19 Controls Option Wiring Schematic A48 7810 ...
Page 105: ...105 Fig 20 Small Chassis Component Location Size 020 035 Units A48 7301 ...
Page 106: ...106 Fig 21 Large Chassis Component Locations Size 036 060 Units A48 7302 ...