Entire Unit Inspection
Items such as : and should be investigated and corrected immediately.
FIG. 4-1 – SHEAVE ALIGNMENT
Always replace belts as a set. Follow the steps below to replace belts:
Never place the belts on the sheaves by using a screw driv er to pry the belt over the rim of the sheave. This will permanently damage the belts
FIG. 4-3 – BELT TENSIONING GAUGE
Filter Drier Replacement
The fi lter/drier should be replaced any time work is per formed on the refrigerant circuit. The rooftop unit comes with sealed type (non-replaceable) cores as stan dard. If the unit is not equipped with the op tion al valve package (suction, discharge, &
If the unit is equipped with a valve pack age, the unit can be pumped down by clos ing the liquid line ball valve (prior to the fi lter/drier) while the unit is running, ini ti at ing a unit pump-down. The unit will shut off when the mechanical low-pres s
Once the fi lter/drier core has been replaced, the fi lter/drier section should be evacuated via the Schrader ac cess valve located next to the fi lter/drier prior to open ing the ball valves and restoring the unit to normal op er a tion.
Forward Curved Fans
This will preserve the bal ance of the ro tat ing as sem bly. Pro ceed with the fol low ing steps:
FIG. 4-4 – EXAMPLE OF FC FAN SHAFT/WHEEL MARKING
DANGER: Disconnect and lock-out power from the unit anytime service is being per- formed on the fan sec tion. Failure to do so could result in serious in ju ry or death due to the fan turning on while work is in progress.
Fan Shaft Bearings
Mounting Details –
Check the shaft - it should be straight, free of burrs and full size. Be sure the bearing is not seated on a worn section of shafting.
NOTE: Shaft should be free from burrs. If old shaft is used, be sure a ball bearing is not seat ed on worn section and shaft is not bent.
Bearing Lock Devices
FIG. 4-5 – BEARING WITH SETSCREW TYPE LOCKING DEVICE
FIG. 4-6 – BEARING WITH ECCENTRIC CAM
CAUTION:Do not apply excessive force to the bear ing hous ing (pillow block or bear ing hous ing (pillow block or fl ange) when installing the bearing flange) when installing the bearing on the shaft.
FIG. 4-7 – ECCENTRIC CAM LOCKING COL LAR BEARING INSTALLATION
TABLE 4-2 – SET SCREW TORQUE
Torquing of Set-screws
CAUTION: After proper installation of the bearing(s), run the unit for 10 to 15 minutes. Shut the unit down and lock it out. Check for proper en gage ment of locking col lar and tight ness of set screw(s).
FIG. 4-8 – SPLIT BEARING