34
SERVICE
Cleaning Evaporator Coil —
Do not use high-pressure
water or air. Damage to fins may result. Clean coils with a vac-
uum cleaner, fresh water, compressed air, or a bristle brush (not
wire). Backflush coil to remove debris. Commercial coil clean-
ers may also be used to help remove grease and dirt. Steam
cleaning is NOT recommended.
Units installed in corrosive environments should be cleaned
as part of a planned maintenance schedule. In this type of appli-
cation, all accumulations of dirt should be cleaned off the coil.
Take care not to get water in the system ducts or unit
insulation.
Lubrication —
Fan motors have permanently lubricated
bearings.
Indoor Fan Adjustment —
To prevent personal injury,
be sure wire fan guards provided by customer are secured in
place over each fan discharge (or that fans are ducted) before
starting the unit.
TO CHANGE FAN SPEED
1. Shut off unit power supply. Lock out power supply and
tag disconnect locations.
2. Loosen fan belt by loosening fan motor belt adjustment
bolts. Do not loosen fan motor mounting bracket from
unit.
3. Loosen movable pulley flange setscrew (Fig. 28).
4. Screw movable flange toward fixed flange to increase fan
speed and away from fixed flange to decrease speed. In-
creasing fan speed increases load on motor. Do not ex-
ceed maximum allowable fan speed or motor full load
amps indicated on unit nameplate and in Table 3.
5. Set movable flange setscrew at nearest flat of pulley hub
and tighten setscrew.
6. Check pulley alignment and belt tension adjustment as
described below.
7. Check fan operation. Repeat above procedure as required.
Pulley Alignment —
Shut off unit power supply. Lock
out power supply and tag disconnect locations. Loosen fan mo-
tor pulley setscrews and slide fan pulley along fan shaft. Make
angular alignment by loosening motor from mounting bracket
(see Fig. 28). Check alignment with a straightedge.
Belt Tension Adjustment —
Shut off unit power sup-
ply. Lock out power supply and tag disconnect locations. Loos-
en fan motor mounting plate bolts. Do not loosen motor
mounting bracket from unit. Adjust belt tensioning bolts until
proper belt tension is obtained.
Changing Fan Wheel —
If a fan wheel should fail, it
may be replaced as follows:
1. Shut off unit power supply. Lock out power supply and
tag disconnect locations.
2. Remove belts from fan pulley.
3. Loosen locking collars on the fan bearings and setscrews
on the fan wheels.
4. Remove the shaft through the access panel on either side
of the unit.
5. Remove the fan cut-off plate in the fan discharge.
6. Remove the fan wheel through the fan discharge opening.
7. Replace the wheel, and reverse Steps 1-5 above.
Fan Bearing Replacement —
If a fan bearing fails,
replace it as follows:
1. Shut off unit power supply. Lock out power supply and
tag disconnect locations.
2. Remove belts from the fan pulley.
3. Support fan shaft.
4. Loosen locking collar on fan bearing.
5. Remove bearing from the shaft.
6. Install new bearing onto the shaft, and reverse Steps 1-4
above.
Concentric Alignment —
Shaft and wheels must be
concentrically centered with the venturi or air inlet of the fan
housing (see Fig. 29).
Shaft bearings are supported by bearing supports (Fig. 30).
If shaft and wheels are concentrically misaligned from ship-
ping shock, it is possible to re-bend the bearing support arms to
the original positions. Replace the bearing support if it has ex-
tensive damage.
Fig. 28 — Fan Pulley Adjustments
a48-916tf
Fig. 29 — Concentric Alignment
a50-2177tf