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| ALL OUTDOOR FANS MUST BE OPERATING |
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(DEG F) | 140 |
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VALVE | 120 |
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| ADD | CHARGE |
| IF ABOVE CURVE |
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LIQUIDAT | 100 |
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TEMPERATURELIQUID |
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80 |
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| 60 |
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| REDUCE CHARGE IF BELOW CURVE |
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| 100 | 150 | 200 | 250 |
| 300 |
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LIQUID PRESSURE AT LIQUID VALVE (PSIG)
Fig. 35 — Cooling Charging Chart
X. GAS VALVE ADJUSTMENT
A. Natural Gas
The gas valve opens and closes in response to the thermostat or limit control.
When power is supplied to valve terminals D1 and C2, the main valve opens to its preset position.
The regular factory setting is stamped on the valve body (3.3 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
4.Set main gas valve to ON position.
5.Set thermostat at setting to call for heat.
6.Remove screw cap covering regulator adjustment screw (See Fig. 36).
7.Turn adjustment screw clockwise to increase pres- sure or counterclockwise to decrease pressure.
8.Once desired pressure is established, set thermostat setting for no call for heat, turn off main gas valve, remove
XI. MAIN BURNERS
For all applications, main burners are factory set and should require no adjustment.
A.Main Burner Removal
1.Shut off
2.Shut off power to unit.
3.Remove unit control box access panel, burner section access panel, and center post (Fig. 4 and 5).
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 2 screws that hold the burner support plate flange to the vestibule plate.
10.Lift burner assembly out of unit.
B. Cleaning and Adjustment
1.Remove burner rack from unit as described in Main Burner Removal section above.
2.Inspect burners, and if dirty, remove burners from rack.
3.Using a soft brush, clean burners and crossover port as required.
4.Adjust spark gap. See Fig. 37.
5.Reinstall burners on rack.
6.Reinstall burner rack as described above.
XII. FILTER DRIER
Replace whenever refrigerant system is exposed to atmosphere.
XIII. PROTECTIVE DEVICES
A. Compressor Protection
Overcurrent
Each compressor has internal line break motor protection.
Overtemperature
Each compressor has an internal protector to protect it against excessively high discharge gas temperatures.
Crankcase Heater
The 581A units are equipped with a
IMPORTANT: After prolonged shutdown or servicing, ener- gize the crankcase heaters for 24 hours before starting the compressors.
Compressor Lockout
If any of the safeties
B. Evaporator Fan Motor Protection
On size 155 units, an internal protector with
On size 180 and 240 units, a manual reset, calibrated trip, magnetic circuit breaker protects against overcurrent. Do not bypass connections or increase the size of the breaker to correct trouble. Determine the cause and correct it before resetting the breaker.