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FORM 145.15-IOM7 (412)
20 JOHNSON CONTROLS
BLOWER SPEED ADJUSTMENT
The RPM of the supply air and condenser air blowers will depend on the required CFM, and the static resistances
of both the supply/discharge and the return/intake duct systems. With this information, the RPM for the blowers
can be determined from the blower performance tables. Adjustment of blower speed is accomplished as follows:
1) Loosen belt tension by moving motor towards the blower shaft via the adjustable mounting.
2) Loosen the setscrew in the adjustable motor pulley flange. Remove external key on pulleys 4 in. diameter and
larger.
3) Blower speed will increase when moveable flange is adjusted towards the fixed flange (closed). Blower speed
will decrease when the moveable flange is adjusted away from the fixed flange (opened). Pulleys are
adjustable only in half-turn increments. Do not open pulley more than five full turns for "4L" and "A" belts, or
six full turns for "B" belts.
4) Once the pulley has been opened/closed the appropriate number of turns, replace the external key and
tighten the adjustment setscrew. Proper torque is 110-130 in.-lbs.
5) Install drive belt and adjust motor mount to tension belt.
LD13547
BELT TENSION ADJUSTMENT
DEFLECTION FORCE VERSUS DRIVE BELT CROSS-SECTION