PULLEY ALIGNMENT Ð For proper belt life, the motor and fan pulleys must be properly aligned. To check, ®rst turn off unit power. Place a straightedge against the motor and fan pulleys. See Fig. 62. If the pulleys are properly aligned, the straightedge should be parallel to the belts.
If they are not parallel, check that the motor shaft and fan shaft are parallel. If they are not, adjust the motor plate adjusting bolts until they are.
After verifying that the shafts are parallel, loosen the set- screws on the motor pulley. Move pulley on the shaft until the pulleys are parallel. To move the sheave on the shaft, loosen the belts. If necessary, blower sheave can also be moved on the shaft.
6.Remove screw cap covering regulator adjustment screw (see Fig. 63).
7.Turn adjustment screw clockwise to increase pressure or counterclockwise to decrease pressure.
8.Once desired pressure is established, set thermostat set- ting for no call for heat, turn off main gas valve, remove
Fig. 62 Ð Pulley Alignment
Gas Valve Adjustment
NATURAL GAS Ð The gas valve opens and closes in re- sponse to the PIC control 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.
Fig. 63 Ð Gas Valve
Main Burners Ð For all applications, main burners are factory set and should require no adjustment.
MAIN BURNER REMOVAL
1.Shut off
2.Shut off power to unit.
3.Remove gas section access door, door frame, and corner post.
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.
Protective Devices
COMPRESSOR PROTECTION
Overcurrent Ð Each compressor has one manual reset, cali- brated trip, magnetic circuit breaker. Do not bypass connec- tions or increase the size of the circuit breaker to correct trouble. Determine the cause and correct it before resetting the breaker.
Crankcase Heater Ð Each compressor has a crankcase heater to prevent absorption of liquid refrigerant by oil in the crank- case when the compressor is idle. Since
IMPORTANT: After a prolonged shutdown or service job, energize the crankcase heaters for 24 hours before starting the compressor.
Compressor Lockout Ð If any of the safeties
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